Code tidy : replace 0 with nullptr or true

49 files changed, 193 insertions, 187 deletions

diff --git a/examples/pdf-attach-file.cc b/examples/pdf-attach-file.cc
index eb12a002..c04f5b9f 100644
--- a/examples/pdf-attach-file.cc
+++ b/examples/pdf-attach-file.cc
@@ -15,7 +15,7 @@
 // the use of the qpdf literal syntax introduced in qpdf 10.6.
 //
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 static void
 usage(std::string const& msg)
@@ -167,11 +167,11 @@ main(int argc, char* argv[])
 {
     whoami = QUtil::getWhoami(argv[0]);
 
-    char const* infilename = 0;
-    char const* password = 0;
-    char const* attachment = 0;
-    char const* outfilename = 0;
-    char const* mimetype = 0;
+    char const* infilename = nullptr;
+    char const* password = nullptr;
+    char const* attachment = nullptr;
+    char const* outfilename = nullptr;
+    char const* mimetype = nullptr;
 
     auto check_arg = [](char const* arg, std::string const& msg) {
         if (arg == nullptr) {
diff --git a/examples/pdf-bookmarks.cc b/examples/pdf-bookmarks.cc
index f6c91b21..1cee51ef 100644
--- a/examples/pdf-bookmarks.cc
+++ b/examples/pdf-bookmarks.cc
@@ -14,7 +14,7 @@
 //
 // Ignore calls to QTC::TC - they are for qpdf CI testing only.
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 static enum { st_none, st_numbers, st_lines } style = st_none;
 static bool show_open = false;
 static bool show_targets = false;
diff --git a/examples/pdf-count-strings.cc b/examples/pdf-count-strings.cc
index 85e05a5f..c762e7f8 100644
--- a/examples/pdf-count-strings.cc
+++ b/examples/pdf-count-strings.cc
@@ -15,7 +15,7 @@
 #include <qpdf/QPDFPageObjectHelper.hh>
 #include <qpdf/QUtil.hh>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-create.cc b/examples/pdf-create.cc
index 785021da..f730b743 100644
--- a/examples/pdf-create.cc
+++ b/examples/pdf-create.cc
@@ -20,7 +20,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 // This is a simple StreamDataProvider that writes image data for an
 // orange square of the given width and height.
diff --git a/examples/pdf-custom-filter.cc b/examples/pdf-custom-filter.cc
index e7877bea..2ea5fd42 100644
--- a/examples/pdf-custom-filter.cc
+++ b/examples/pdf-custom-filter.cc
@@ -37,7 +37,7 @@
 // of running this example on test files that are specifically crafted
 // for it.
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 class Pl_XOR: public Pipeline
 {
@@ -447,8 +447,8 @@ main(int argc, char* argv[])
 {
     whoami = QUtil::getWhoami(argv[0]);
 
-    char const* infilename = 0;
-    char const* outfilename = 0;
+    char const* infilename = nullptr;
+    char const* outfilename = nullptr;
     bool decode_specialized = false;
     for (int i = 1; i < argc; ++i) {
         if (strcmp(argv[i], "--decode-specialized") == 0) {
diff --git a/examples/pdf-double-page-size.cc b/examples/pdf-double-page-size.cc
index f0f86d02..fb0584e9 100644
--- a/examples/pdf-double-page-size.cc
+++ b/examples/pdf-double-page-size.cc
@@ -8,7 +8,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-filter-tokens.cc b/examples/pdf-filter-tokens.cc
index ccacc8c2..c9a71e64 100644
--- a/examples/pdf-filter-tokens.cc
+++ b/examples/pdf-filter-tokens.cc
@@ -18,7 +18,7 @@
 #include <qpdf/QPDFWriter.hh>
 #include <qpdf/QUtil.hh>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-invert-images.cc b/examples/pdf-invert-images.cc
index 94392ac3..9ffb9c1f 100644
--- a/examples/pdf-invert-images.cc
+++ b/examples/pdf-invert-images.cc
@@ -9,7 +9,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
@@ -142,7 +142,8 @@ main(int argc, char* argv[])
                 // pipeStreamData with a null pipeline to determine
                 // whether the image is filterable.  Directly inspect
                 // keys to determine the image type.
-                if (image.pipeStreamData(0, qpdf_ef_compress, qpdf_dl_all) &&
+                if (image.pipeStreamData(
+                        nullptr, qpdf_ef_compress, qpdf_dl_all) &&
                     color_space.isNameAndEquals("/DeviceGray") &&
                     bits_per_component.isInteger() &&
                     (bits_per_component.getIntValue() == 8)) {
diff --git a/examples/pdf-mod-info.cc b/examples/pdf-mod-info.cc
index 2b8e3c47..fa49738b 100644
--- a/examples/pdf-mod-info.cc
+++ b/examples/pdf-mod-info.cc
@@ -11,7 +11,7 @@
 #include <string.h>
 
 static char const* version = "1.1";
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
@@ -77,8 +77,8 @@ main(int argc, char* argv[])
         exit(0);
     }
 
-    char* fl_in = 0;
-    char* fl_out = 0;
+    char* fl_in = nullptr;
+    char* fl_out = nullptr;
     std::string cur_key;
 
     for (int i = 1; i < argc; ++i) {
diff --git a/examples/pdf-name-number-tree.cc b/examples/pdf-name-number-tree.cc
index 939105e9..381085ba 100644
--- a/examples/pdf-name-number-tree.cc
+++ b/examples/pdf-name-number-tree.cc
@@ -6,7 +6,7 @@
 #include <cstring>
 #include <iostream>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-npages.cc b/examples/pdf-npages.cc
index f430935c..3d34d489 100644
--- a/examples/pdf-npages.cc
+++ b/examples/pdf-npages.cc
@@ -5,7 +5,7 @@
 #include <qpdf/QPDF.hh>
 #include <qpdf/QUtil.hh>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-overlay-page.cc b/examples/pdf-overlay-page.cc
index 594f139e..d055d279 100644
--- a/examples/pdf-overlay-page.cc
+++ b/examples/pdf-overlay-page.cc
@@ -12,7 +12,7 @@
 // --overlay and --underlay options provide a more general version of
 // this capability.
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-parse-content.cc b/examples/pdf-parse-content.cc
index 6bc94da2..481633e6 100644
--- a/examples/pdf-parse-content.cc
+++ b/examples/pdf-parse-content.cc
@@ -8,7 +8,7 @@
 #include <qpdf/QPDFPageObjectHelper.hh>
 #include <qpdf/QUtil.hh>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/pdf-set-form-values.cc b/examples/pdf-set-form-values.cc
index cc328cf3..1398c0dd 100644
--- a/examples/pdf-set-form-values.cc
+++ b/examples/pdf-set-form-values.cc
@@ -8,7 +8,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 void
 usage()
diff --git a/examples/qpdf-job.cc b/examples/qpdf-job.cc
index b71b612a..614abbe6 100644
--- a/examples/qpdf-job.cc
+++ b/examples/qpdf-job.cc
@@ -8,7 +8,7 @@
 // This program is a simple demonstration of different ways to use the
 // QPDFJob API.
 
-static char const* whoami = 0;
+static char const* whoami = nullptr;
 
 static void
 usage()
diff --git a/libqpdf/Buffer.cc b/libqpdf/Buffer.cc
index 91bacc8e..4e8a17ae 100644
--- a/libqpdf/Buffer.cc
+++ b/libqpdf/Buffer.cc
@@ -5,10 +5,10 @@
 Buffer::Members::Members(size_t size, unsigned char* buf, bool own_memory) :
     own_memory(own_memory),
     size(size),
-    buf(0)
+    buf(nullptr)
 {
     if (own_memory) {
-        this->buf = (size ? new unsigned char[size] : 0);
+        this->buf = (size ? new unsigned char[size] : nullptr);
     } else {
         this->buf = buf;
     }
@@ -22,12 +22,12 @@ Buffer::Members::~Members()
 }
 
 Buffer::Buffer() :
-    m(new Members(0, 0, true))
+    m(new Members(0, nullptr, true))
 {
 }
 
 Buffer::Buffer(size_t size) :
-    m(new Members(size, 0, true))
+    m(new Members(size, nullptr, true))
 {
 }
 
@@ -52,7 +52,8 @@ void
 Buffer::copy(Buffer const& rhs)
 {
     if (this != &rhs) {
-        this->m = std::shared_ptr<Members>(new Members(rhs.m->size, 0, true));
+        this->m =
+            std::shared_ptr<Members>(new Members(rhs.m->size, nullptr, true));
         if (this->m->size) {
             memcpy(this->m->buf, rhs.m->buf, this->m->size);
         }
diff --git a/libqpdf/BufferInputSource.cc b/libqpdf/BufferInputSource.cc
index 033ef265..5b59c801 100644
--- a/libqpdf/BufferInputSource.cc
+++ b/libqpdf/BufferInputSource.cc
@@ -25,7 +25,7 @@ BufferInputSource::BufferInputSource(
 
 BufferInputSource::BufferInputSource(
     std::string const& description, std::string const& contents) :
-    m(new Members(true, description, 0))
+    m(new Members(true, description, nullptr))
 {
     this->m->buf = new Buffer(contents.length());
     this->m->max_offset = QIntC::to_offset(this->m->buf->getSize());
diff --git a/libqpdf/ClosedFileInputSource.cc b/libqpdf/ClosedFileInputSource.cc
index 7d49bf70..dfb98c6a 100644
--- a/libqpdf/ClosedFileInputSource.cc
+++ b/libqpdf/ClosedFileInputSource.cc
@@ -23,7 +23,7 @@ ClosedFileInputSource::~ClosedFileInputSource()
 void
 ClosedFileInputSource::before()
 {
-    if (0 == this->m->fis.get()) {
+    if (nullptr == this->m->fis.get()) {
         this->m->fis =
             std::make_shared<FileInputSource>(this->m->filename.c_str());
         this->m->fis->seek(this->m->offset, SEEK_SET);
@@ -39,7 +39,7 @@ ClosedFileInputSource::after()
     if (this->m->stay_open) {
         return;
     }
-    this->m->fis = 0;
+    this->m->fis = nullptr;
 }
 
 qpdf_offset_t
diff --git a/libqpdf/FileInputSource.cc b/libqpdf/FileInputSource.cc
index 08b35056..ab88d302 100644
--- a/libqpdf/FileInputSource.cc
+++ b/libqpdf/FileInputSource.cc
@@ -7,7 +7,7 @@
 
 FileInputSource::Members::Members(bool close_file) :
     close_file(close_file),
-    file(0)
+    file(nullptr)
 {
 }
 
diff --git a/libqpdf/InputSource.cc b/libqpdf/InputSource.cc
index ba4c3cbc..33ab44d1 100644
--- a/libqpdf/InputSource.cc
+++ b/libqpdf/InputSource.cc
@@ -69,7 +69,7 @@ InputSource::findFirst(
             " too small or too large of a character sequence");
     }
 
-    char* p = 0;
+    char* p = nullptr;
     qpdf_offset_t buf_offset = offset;
     size_t bytes_read = 0;
 
@@ -86,7 +86,8 @@ InputSource::findFirst(
         // If p points to buf[size], since strlen(start_chars) is
         // always >= 1, this overflow test will be correct for that
         // case regardless of start_chars.
-        if ((p == 0) || ((p + strlen(start_chars)) > (buf + bytes_read))) {
+        if ((p == nullptr) ||
+            ((p + strlen(start_chars)) > (buf + bytes_read))) {
             if (p) {
                 QTC::TC(
                     "libtests",
@@ -117,7 +118,7 @@ InputSource::findFirst(
                  memchr(
                      p,
                      start_chars[0],
-                     bytes_read - QIntC::to_size(p - buf)))) != 0) {
+                     bytes_read - QIntC::to_size(p - buf)))) != nullptr) {
             if (p == buf) {
                 QTC::TC("libtests", "InputSource found match at buf[0]");
             }
diff --git a/libqpdf/JSON.cc b/libqpdf/JSON.cc
index 8f4e75a2..1796c859 100644
--- a/libqpdf/JSON.cc
+++ b/libqpdf/JSON.cc
@@ -204,7 +204,7 @@ JSON::JSON_blob::write(Pipeline* p, size_t) const
 void
 JSON::write(Pipeline* p, size_t depth) const
 {
-    if (0 == this->m->value.get()) {
+    if (nullptr == this->m->value.get()) {
         *p << "null";
     } else {
         this->m->value->write(p, depth);
@@ -270,7 +270,7 @@ JSON
 JSON::addDictionaryMember(std::string const& key, JSON const& val)
 {
     JSON_dictionary* obj = dynamic_cast<JSON_dictionary*>(this->m->value.get());
-    if (0 == obj) {
+    if (nullptr == obj) {
         throw std::runtime_error(
             "JSON::addDictionaryMember called on non-dictionary");
     }
@@ -286,7 +286,7 @@ bool
 JSON::checkDictionaryKeySeen(std::string const& key)
 {
     JSON_dictionary* obj = dynamic_cast<JSON_dictionary*>(this->m->value.get());
-    if (0 == obj) {
+    if (nullptr == obj) {
         throw std::logic_error(
             "JSON::checkDictionaryKey called on non-dictionary");
     }
@@ -307,7 +307,7 @@ JSON
 JSON::addArrayElement(JSON const& val)
 {
     JSON_array* arr = dynamic_cast<JSON_array*>(this->m->value.get());
-    if (0 == arr) {
+    if (nullptr == arr) {
         throw std::runtime_error("JSON::addArrayElement called on non-array");
     }
     if (val.m->value.get()) {
diff --git a/libqpdf/Pipeline.cc b/libqpdf/Pipeline.cc
index 5bd4557d..6f3f33db 100644
--- a/libqpdf/Pipeline.cc
+++ b/libqpdf/Pipeline.cc
@@ -14,7 +14,7 @@ Pipeline::Pipeline(char const* identifier, Pipeline* next) :
 Pipeline*
 Pipeline::getNext(bool allow_null)
 {
-    if ((this->next == 0) && (!allow_null)) {
+    if ((this->next == nullptr) && (!allow_null)) {
         throw std::logic_error(
             this->identifier +
             ": Pipeline::getNext() called on pipeline with no next");
diff --git a/libqpdf/Pl_Buffer.cc b/libqpdf/Pl_Buffer.cc
index 829d0e7c..c7e3f923 100644
--- a/libqpdf/Pl_Buffer.cc
+++ b/libqpdf/Pl_Buffer.cc
@@ -26,7 +26,7 @@ Pl_Buffer::~Pl_Buffer()
 void
 Pl_Buffer::write(unsigned char const* buf, size_t len)
 {
-    if (this->m->data.get() == 0) {
+    if (this->m->data.get() == nullptr) {
         this->m->data = std::make_shared<Buffer>(len);
     }
     size_t cur_size = this->m->data->getSize();
diff --git a/libqpdf/Pl_Discard.cc b/libqpdf/Pl_Discard.cc
index 4e0da6fc..f1078e3a 100644
--- a/libqpdf/Pl_Discard.cc
+++ b/libqpdf/Pl_Discard.cc
@@ -3,7 +3,7 @@
 // Exercised in md5 test suite
 
 Pl_Discard::Pl_Discard() :
-    Pipeline("discard", 0)
+    Pipeline("discard", nullptr)
 {
 }
 
diff --git a/libqpdf/Pl_Flate.cc b/libqpdf/Pl_Flate.cc
index 3ce7f434..4183b7e4 100644
--- a/libqpdf/Pl_Flate.cc
+++ b/libqpdf/Pl_Flate.cc
@@ -13,7 +13,7 @@ Pl_Flate::Members::Members(size_t out_bufsize, action_e action) :
     out_bufsize(out_bufsize),
     action(action),
     initialized(false),
-    zdata(0)
+    zdata(nullptr)
 {
     this->outbuf = QUtil::make_shared_array<unsigned char>(out_bufsize);
     // Indirect through zdata to reach the z_stream so we don't have
@@ -29,10 +29,10 @@ Pl_Flate::Members::Members(size_t out_bufsize, action_e action) :
     }
 
     z_stream& zstream = *(static_cast<z_stream*>(this->zdata));
-    zstream.zalloc = 0;
-    zstream.zfree = 0;
-    zstream.opaque = 0;
-    zstream.next_in = 0;
+    zstream.zalloc = nullptr;
+    zstream.zfree = nullptr;
+    zstream.opaque = nullptr;
+    zstream.next_in = nullptr;
     zstream.avail_in = 0;
     zstream.next_out = this->outbuf.get();
     zstream.avail_out = QIntC::to_uint(out_bufsize);
@@ -50,7 +50,7 @@ Pl_Flate::Members::~Members()
     }
 
     delete static_cast<z_stream*>(this->zdata);
-    this->zdata = 0;
+    this->zdata = nullptr;
 }
 
 Pl_Flate::Pl_Flate(
@@ -86,7 +86,7 @@ Pl_Flate::warn(char const* msg, int code)
 void
 Pl_Flate::write(unsigned char const* data, size_t len)
 {
-    if (this->m->outbuf.get() == 0) {
+    if (this->m->outbuf.get() == nullptr) {
         throw std::logic_error(
             this->identifier +
             ": Pl_Flate: write() called after finish() called");
@@ -227,7 +227,7 @@ Pl_Flate::finish()
                 checkError("End", err);
             }
 
-            this->m->outbuf = 0;
+            this->m->outbuf = nullptr;
         }
     } catch (std::exception& e) {
         try {
diff --git a/libqpdf/Pl_LZWDecoder.cc b/libqpdf/Pl_LZWDecoder.cc
index 3a381899..7d02f291 100644
--- a/libqpdf/Pl_LZWDecoder.cc
+++ b/libqpdf/Pl_LZWDecoder.cc
@@ -14,7 +14,7 @@ Pl_LZWDecoder::Pl_LZWDecoder(
     byte_pos(0),
     bit_pos(0),
     bits_available(0),
-    code_change_delta(early_code_change ? 1 : 0),
+    code_change_delta(early_code_change),
     eod(false),
     last_code(256)
 {
@@ -107,7 +107,7 @@ void
 Pl_LZWDecoder::addToTable(unsigned char next)
 {
     unsigned int last_size = 0;
-    unsigned char const* last_data = 0;
+    unsigned char const* last_data = nullptr;
     unsigned char tmp[1];
 
     if (this->last_code < 256) {
diff --git a/libqpdf/Pl_OStream.cc b/libqpdf/Pl_OStream.cc
index db0081df..137b6654 100644
--- a/libqpdf/Pl_OStream.cc
+++ b/libqpdf/Pl_OStream.cc
@@ -10,7 +10,7 @@ Pl_OStream::Members::Members(std::ostream& os) :
 }
 
 Pl_OStream::Pl_OStream(char const* identifier, std::ostream& os) :
-    Pipeline(identifier, 0),
+    Pipeline(identifier, nullptr),
     m(new Members(os))
 {
 }
diff --git a/libqpdf/Pl_PNGFilter.cc b/libqpdf/Pl_PNGFilter.cc
index 7914b3b6..e2a9a0db 100644
--- a/libqpdf/Pl_PNGFilter.cc
+++ b/libqpdf/Pl_PNGFilter.cc
@@ -22,10 +22,10 @@ Pl_PNGFilter::Pl_PNGFilter(
     unsigned int bits_per_sample) :
     Pipeline(identifier, next),
     action(action),
-    cur_row(0),
-    prev_row(0),
-    buf1(0),
-    buf2(0),
+    cur_row(nullptr),
+    prev_row(nullptr),
+    buf1(nullptr),
+    buf2(nullptr),
     pos(0)
 {
     if (samples_per_pixel < 1) {
@@ -243,7 +243,7 @@ Pl_PNGFilter::finish()
         // write partial row
         processRow();
     }
-    this->prev_row = 0;
+    this->prev_row = nullptr;
     this->cur_row = buf1.get();
     this->pos = 0;
     memset(this->cur_row, 0, this->bytes_per_row + 1);
diff --git a/libqpdf/Pl_QPDFTokenizer.cc b/libqpdf/Pl_QPDFTokenizer.cc
index 85b5fcce..9082538d 100644
--- a/libqpdf/Pl_QPDFTokenizer.cc
+++ b/libqpdf/Pl_QPDFTokenizer.cc
@@ -7,7 +7,7 @@
 #include <string.h>
 
 Pl_QPDFTokenizer::Members::Members() :
-    filter(0),
+    filter(nullptr),
     buf("tokenizer buffer")
 {
 }
@@ -68,7 +68,8 @@ Pl_QPDFTokenizer::finish()
         }
     }
     this->m->filter->handleEOF();
-    QPDFObjectHandle::TokenFilter::PipelineAccessor::setPipeline(m->filter, 0);
+    QPDFObjectHandle::TokenFilter::PipelineAccessor::setPipeline(
+        m->filter, nullptr);
     Pipeline* next = this->getNext(true);
     if (next) {
         next->finish();
diff --git a/libqpdf/Pl_RC4.cc b/libqpdf/Pl_RC4.cc
index 1f64b5d3..823b22ea 100644
--- a/libqpdf/Pl_RC4.cc
+++ b/libqpdf/Pl_RC4.cc
@@ -18,7 +18,7 @@ Pl_RC4::Pl_RC4(
 void
 Pl_RC4::write(unsigned char const* data, size_t len)
 {
-    if (this->outbuf.get() == 0) {
+    if (this->outbuf.get() == nullptr) {
         throw std::logic_error(
             this->identifier +
             ": Pl_RC4: write() called after finish() called");
@@ -41,6 +41,6 @@ Pl_RC4::write(unsigned char const* data, size_t len)
 void
 Pl_RC4::finish()
 {
-    this->outbuf = 0;
+    this->outbuf = nullptr;
     this->getNext()->finish();
 }
diff --git a/libqpdf/Pl_StdioFile.cc b/libqpdf/Pl_StdioFile.cc
index 2415ef96..dca16bf6 100644
--- a/libqpdf/Pl_StdioFile.cc
+++ b/libqpdf/Pl_StdioFile.cc
@@ -12,7 +12,7 @@ Pl_StdioFile::Members::Members(FILE* f) :
 }
 
 Pl_StdioFile::Pl_StdioFile(char const* identifier, FILE* f) :
-    Pipeline(identifier, 0),
+    Pipeline(identifier, nullptr),
     m(new Members(f))
 {
 }
diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index a0f0f9e1..c2c764db 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -216,7 +216,7 @@ QPDF::Members::Members() :
     pushed_inherited_attributes_to_pages(false),
     ever_pushed_inherited_attributes_to_pages(false),
     ever_called_get_all_pages(false),
-    copied_stream_data_provider(0),
+    copied_stream_data_provider(nullptr),
     reconstructed_xref(false),
     fixed_dangling_refs(false),
     immediate_copy_from(false),
@@ -1496,7 +1496,7 @@ QPDF::readObject(
 
     bool empty = false;
     std::shared_ptr<StringDecrypter> decrypter_ph;
-    StringDecrypter* decrypter = 0;
+    StringDecrypter* decrypter = nullptr;
     if (this->m->encp->encrypted && (!in_object_stream)) {
         decrypter_ph = std::make_shared<StringDecrypter>(this, og);
         decrypter = decrypter_ph.get();
@@ -2434,7 +2434,7 @@ QPDF::copyStreamData(QPDFObjectHandle result, QPDFObjectHandle foreign)
 
     QPDFObjectHandle dict = result.getDict();
     QPDFObjectHandle old_dict = foreign.getDict();
-    if (this->m->copied_stream_data_provider == 0) {
+    if (this->m->copied_stream_data_provider == nullptr) {
         this->m->copied_stream_data_provider =
             new CopiedStreamDataProvider(*this);
         this->m->copied_streams =
@@ -2457,7 +2457,7 @@ QPDF::copyStreamData(QPDFObjectHandle result, QPDFObjectHandle foreign)
     }
     std::shared_ptr<Buffer> stream_buffer = stream->getStreamDataBuffer();
     if ((foreign_stream_qpdf->m->immediate_copy_from) &&
-        (stream_buffer.get() == 0)) {
+        (stream_buffer.get() == nullptr)) {
         // Pull the stream data into a buffer before attempting
         // the copy operation. Do it on the source stream so that
         // if the source stream is copied multiple times, we don't
diff --git a/libqpdf/QPDFArgParser.cc b/libqpdf/QPDFArgParser.cc
index c58edec7..89bf5ad1 100644
--- a/libqpdf/QPDFArgParser.cc
+++ b/libqpdf/QPDFArgParser.cc
@@ -30,7 +30,7 @@ QPDFArgParser::QPDFArgParser(
     m(new Members(argc, argv, progname_env))
 {
     selectHelpOptionTable();
-    char const* help_choices[] = {"all", 0};
+    char const* help_choices[] = {"all", nullptr};
     // More help choices are added dynamically.
     addChoices(
         "help", bindParam(&QPDFArgParser::argHelp, this), false, help_choices);
@@ -254,7 +254,7 @@ QPDFArgParser::handleArgFileArguments()
     // deleted by using shared pointers to back the pointers in argv.
     this->m->new_argv.push_back(QUtil::make_shared_cstr(this->m->argv[0]));
     for (int i = 1; i < this->m->argc; ++i) {
-        char const* argfile = 0;
+        char const* argfile = nullptr;
         if ((strlen(this->m->argv[i]) > 1) && (this->m->argv[i][0] == '@')) {
             argfile = 1 + this->m->argv[i];
             if (strcmp(argfile, "-") != 0) {
diff --git a/libqpdf/QPDFCrypto_native.cc b/libqpdf/QPDFCrypto_native.cc
index 458e90cb..5cd3c887 100644
--- a/libqpdf/QPDFCrypto_native.cc
+++ b/libqpdf/QPDFCrypto_native.cc
@@ -14,7 +14,7 @@ getRandomProvider()
     static RandomDataProvider* insecure_random_data_provider =
         InsecureRandomDataProvider::getInstance();
 #else
-    static RandomDataProvider* insecure_random_data_provider = 0;
+    static RandomDataProvider* insecure_random_data_provider = nullptr;
 #endif
     static RandomDataProvider* secure_random_data_provider =
         SecureRandomDataProvider::getInstance();
@@ -22,9 +22,9 @@ getRandomProvider()
     static RandomDataProvider* provider =
         (secure_random_data_provider         ? secure_random_data_provider
              : insecure_random_data_provider ? insecure_random_data_provider
-                                             : 0);
+                                             : nullptr);
 
-    if (provider == 0) {
+    if (provider == nullptr) {
         throw std::logic_error("QPDFCrypto_native has no random data provider");
     }
 
diff --git a/libqpdf/QPDFFormFieldObjectHelper.cc b/libqpdf/QPDFFormFieldObjectHelper.cc
index 6373f04f..5ff41edd 100644
--- a/libqpdf/QPDFFormFieldObjectHelper.cc
+++ b/libqpdf/QPDFFormFieldObjectHelper.cc
@@ -746,7 +746,7 @@ TfFinder::handleToken(QPDFTokenizer::Token const& token)
     switch (ttype) {
     case QPDFTokenizer::tt_integer:
     case QPDFTokenizer::tt_real:
-        last_num = strtod(value.c_str(), 0);
+        last_num = strtod(value.c_str(), nullptr);
         last_num_idx = QIntC::to_int(DA.size() - 1);
         break;
 
@@ -785,7 +785,7 @@ TfFinder::getDA()
     for (size_t i = 0; i < n; ++i) {
         std::string cur = this->DA.at(i);
         if (QIntC::to_int(i) == tf_idx) {
-            double delta = strtod(cur.c_str(), 0) - this->tf;
+            double delta = strtod(cur.c_str(), nullptr) - this->tf;
             if ((delta > 0.001) || (delta < -0.001)) {
                 // tf doesn't match the font size passed to Tf, so
                 // substitute.
diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index 343fa348..26425def 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -211,7 +211,7 @@ ImageOptimizer::makePipeline(std::string const& description, Pipeline* next)
 bool
 ImageOptimizer::evaluate(std::string const& description)
 {
-    if (!image.pipeStreamData(0, 0, qpdf_dl_specialized, true)) {
+    if (!image.pipeStreamData(nullptr, 0, qpdf_dl_specialized, true)) {
         QTC::TC("qpdf", "QPDFJob image optimize no pipeline");
         o.doIfVerbose([&](Pipeline& v, std::string const& prefix) {
             v << prefix << ": " << description
@@ -317,7 +317,7 @@ QPDFJob::Members::Members() :
     warnings(false),
     encryption_status(0),
     verbose(false),
-    password(0),
+    password(nullptr),
     linearize(false),
     decrypt(false),
     split_pages(0),
@@ -326,7 +326,7 @@ QPDFJob::Members::Members() :
     suppress_warnings(false),
     warnings_exit_zero(false),
     copy_encryption(false),
-    encryption_file_password(0),
+    encryption_file_password(nullptr),
     encrypt(false),
     password_is_hex_key(false),
     suppress_password_recovery(false),
@@ -411,7 +411,7 @@ QPDFJob::Members::Members() :
     ii_min_bytes(DEFAULT_II_MIN_BYTES),
     underlay("underlay"),
     overlay("overlay"),
-    under_overlay(0),
+    under_overlay(nullptr),
     require_outfile(true),
     replace_input(false),
     check_is_encrypted(false),
@@ -673,13 +673,15 @@ QPDFJob::checkConfiguration()
             usage("--split-pages may not be used with --replace-input");
         }
     }
-    if (m->infilename == 0) {
+    if (m->infilename == nullptr) {
         usage("an input file name is required");
     } else if (
-        m->require_outfile && (m->outfilename == 0) && (!m->replace_input)) {
+        m->require_outfile && (m->outfilename == nullptr) &&
+        (!m->replace_input)) {
         usage("an output file name is required; use - for standard output");
     } else if (
-        (!m->require_outfile) && ((m->outfilename != 0) || m->replace_input)) {
+        (!m->require_outfile) &&
+        ((m->outfilename != nullptr) || m->replace_input)) {
         usage("no output file may be given for this option");
     }
     if (m->check_requires_password && m->check_is_encrypted) {
@@ -924,7 +926,7 @@ QPDFJob::doShowObj(QPDF& pdf)
     if (obj.isStream()) {
         if (m->show_raw_stream_data || m->show_filtered_stream_data) {
             bool filter = m->show_filtered_stream_data;
-            if (filter && (!obj.pipeStreamData(0, 0, qpdf_dl_all))) {
+            if (filter && (!obj.pipeStreamData(nullptr, 0, qpdf_dl_all))) {
                 QTC::TC("qpdf", "QPDFJob unable to filter");
                 obj.warnIfPossible("unable to filter stream data");
                 error = true;
@@ -1204,7 +1206,7 @@ QPDFJob::doJSONPages(Pipeline* p, bool& first, QPDF& pdf)
             j_image.addDictionaryMember(
                 "filterable",
                 JSON::makeBool(
-                    image.pipeStreamData(0, 0, m->decode_level, true)));
+                    image.pipeStreamData(nullptr, 0, m->decode_level, true)));
         }
         j_page.addDictionaryMember("images", j_images);
         JSON j_contents =
@@ -1561,7 +1563,7 @@ QPDFJob::json_schema(int json_version, std::set<std::string>* keys)
   "decodelevel": "decode level used to determine stream filterability"
 })"));
 
-    bool all_keys = ((keys == 0) || keys->empty());
+    bool all_keys = ((keys == nullptr) || keys->empty());
 
     // The list of selectable top-level keys id duplicated in the
     // following places: job.yml, QPDFJob::json_schema, and
@@ -1943,7 +1945,7 @@ QPDFJob::doProcess(
             password = ptemp.c_str();
         }
     }
-    if ((password == 0) || empty || m->password_is_hex_key ||
+    if ((password == nullptr) || empty || m->password_is_hex_key ||
         m->suppress_password_recovery) {
         // There is no password, or we're not doing recovery, so just
         // do the normal processing with the supplied password.
@@ -2591,7 +2593,7 @@ QPDFJob::handlePageSpecs(
             // to the same underlying file with the same path to
             // achieve the same affect.
             char const* password = page_spec.password.get();
-            if ((!m->encryption_file.empty()) && (password == 0) &&
+            if ((!m->encryption_file.empty()) && (password == nullptr) &&
                 (page_spec.filename == m->encryption_file)) {
                 QTC::TC("qpdf", "QPDFJob pages encryption password");
                 password = m->encryption_file_password.get();
@@ -2600,7 +2602,7 @@ QPDFJob::handlePageSpecs(
                 v << prefix << ": processing " << page_spec.filename << "\n";
             });
             std::shared_ptr<InputSource> is;
-            ClosedFileInputSource* cis = 0;
+            ClosedFileInputSource* cis = nullptr;
             if (!m->keep_files_open) {
                 QTC::TC("qpdf", "QPDFJob keep files open n");
                 cis = new ClosedFileInputSource(page_spec.filename.c_str());
@@ -2636,7 +2638,7 @@ QPDFJob::handlePageSpecs(
     if (m->remove_unreferenced_page_resources != QPDFJob::re_no) {
         for (auto const& iter: page_spec_qpdfs) {
             std::string const& filename = iter.first;
-            ClosedFileInputSource* cis = 0;
+            ClosedFileInputSource* cis = nullptr;
             if (page_spec_cfis.count(filename)) {
                 cis = page_spec_cfis[filename];
                 cis->stayOpen(true);
@@ -2707,7 +2709,7 @@ QPDFJob::handlePageSpecs(
     auto this_afdh = get_afdh_for_qpdf(afdh_map, &pdf);
     std::set<QPDFObjGen> referenced_fields;
     for (auto& page_data: parsed_specs) {
-        ClosedFileInputSource* cis = 0;
+        ClosedFileInputSource* cis = nullptr;
         if (page_spec_cfis.count(page_data.filename)) {
             cis = page_spec_cfis[page_data.filename];
             cis->stayOpen(true);
@@ -3061,7 +3063,7 @@ parse_version(
     auto vp = QUtil::make_unique_cstr(full_version_string);
     char* v = vp.get();
     char* p1 = strchr(v, '.');
-    char* p2 = (p1 ? strchr(1 + p1, '.') : 0);
+    char* p2 = (p1 ? strchr(1 + p1, '.') : nullptr);
     if (p2 && *(p2 + 1)) {
         *p2++ = '\0';
         extension_level = QUtil::string_to_int(p2);
@@ -3176,7 +3178,7 @@ QPDFJob::doSplitPages(QPDF& pdf, bool& warnings)
     std::string after;
     size_t len = strlen(m->outfilename.get());
     char* num_spot = strstr(const_cast<char*>(m->outfilename.get()), "%d");
-    if (num_spot != 0) {
+    if (num_spot != nullptr) {
         QTC::TC("qpdf", "QPDFJob split-pages %d");
         before = std::string(
             m->outfilename.get(),
@@ -3310,7 +3312,7 @@ QPDFJob::writeOutfile(QPDF& pdf)
         });
     }
     if (m->replace_input) {
-        m->outfilename = 0;
+        m->outfilename = nullptr;
     }
     if (m->replace_input) {
         // We must close the input before we can rename files
diff --git a/libqpdf/QPDFJob_config.cc b/libqpdf/QPDFJob_config.cc
index b9b53ebd..0192346e 100644
--- a/libqpdf/QPDFJob_config.cc
+++ b/libqpdf/QPDFJob_config.cc
@@ -13,7 +13,7 @@ QPDFJob::Config::checkConfiguration()
 QPDFJob::Config*
 QPDFJob::Config::inputFile(std::string const& filename)
 {
-    if (o.m->infilename == 0) {
+    if (o.m->infilename == nullptr) {
         o.m->infilename = QUtil::make_shared_cstr(filename);
     } else {
         usage("input file has already been given");
@@ -24,7 +24,7 @@ QPDFJob::Config::inputFile(std::string const& filename)
 QPDFJob::Config*
 QPDFJob::Config::emptyInput()
 {
-    if (o.m->infilename == 0) {
+    if (o.m->infilename == nullptr) {
         // Various places in QPDFJob.cc know that the empty string for
         // infile means empty. We set it to something other than a
         // null pointer as an indication that some input source has
@@ -44,7 +44,7 @@ QPDFJob::Config::emptyInput()
 QPDFJob::Config*
 QPDFJob::Config::outputFile(std::string const& filename)
 {
-    if ((o.m->outfilename == 0) && (!o.m->replace_input)) {
+    if ((o.m->outfilename == nullptr) && (!o.m->replace_input)) {
         o.m->outfilename = QUtil::make_shared_cstr(filename);
     } else {
         usage("output file has already been given");
@@ -55,7 +55,7 @@ QPDFJob::Config::outputFile(std::string const& filename)
 QPDFJob::Config*
 QPDFJob::Config::replaceInput()
 {
-    if ((o.m->outfilename == 0) && (!o.m->replace_input)) {
+    if ((o.m->outfilename == nullptr) && (!o.m->replace_input)) {
         o.m->replace_input = true;
     } else {
         usage("replace-input can't be used"
@@ -977,7 +977,7 @@ QPDFJob::UOConfig::endUnderlayOverlay()
     if (config->o.m->under_overlay->filename.empty()) {
         usage(config->o.m->under_overlay->which + " file not specified");
     }
-    config->o.m->under_overlay = 0;
+    config->o.m->under_overlay = nullptr;
     return this->config;
 }
 
diff --git a/libqpdf/QPDFObject.cc b/libqpdf/QPDFObject.cc
index 39a5fa50..382dd6c6 100644
--- a/libqpdf/QPDFObject.cc
+++ b/libqpdf/QPDFObject.cc
@@ -1,7 +1,7 @@
 #include <qpdf/QPDFObject.hh>
 
 QPDFObject::QPDFObject() :
-    owning_qpdf(0),
+    owning_qpdf(nullptr),
     parsed_offset(-1)
 {
 }
@@ -25,13 +25,13 @@ QPDFObject::getDescription(QPDF*& qpdf, std::string& description)
 {
     qpdf = this->owning_qpdf;
     description = this->object_description;
-    return this->owning_qpdf != 0;
+    return this->owning_qpdf != nullptr;
 }
 
 bool
 QPDFObject::hasDescription()
 {
-    return this->owning_qpdf != 0;
+    return this->owning_qpdf != nullptr;
 }
 
 void
diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index 753493ec..bfbc19f9 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -265,7 +265,7 @@ QPDFObjectHandle::releaseResolved()
     // destruction.  See comments in QPDF::~QPDF().
     if (isIndirect()) {
         if (this->obj.get()) {
-            this->obj = 0;
+            this->obj = nullptr;
         }
     } else {
         QPDFObject::ObjAccessor::releaseResolved(this->obj.get());
@@ -780,7 +780,7 @@ QPDFObjectHandle::getArrayItem(int n)
             typeWarning("array", "returning null");
             QTC::TC("qpdf", "QPDFObjectHandle array null for non-array");
         }
-        QPDF* context = 0;
+        QPDF* context = nullptr;
         std::string description;
         if (this->obj->getDescription(context, description)) {
             result.setObjectDescription(
@@ -998,7 +998,7 @@ QPDFObjectHandle::getKey(std::string const& key)
         typeWarning("dictionary", "returning null for attempted key retrieval");
         QTC::TC("qpdf", "QPDFObjectHandle dictionary null for getKey");
         result = newNull();
-        QPDF* qpdf = 0;
+        QPDF* qpdf = nullptr;
         std::string description;
         if (this->obj->getDescription(qpdf, description)) {
             result.setObjectDescription(
@@ -1655,7 +1655,7 @@ QPDFObjectHandle::coalesceContentStreams()
         return;
     }
     QPDF* qpdf = getOwningQPDF();
-    if (qpdf == 0) {
+    if (qpdf == nullptr) {
         // Should not be possible for a page object to not have an
         // owning PDF unless it was manually constructed in some
         // incorrect way. However, it can happen in a PDF file whose
@@ -1772,7 +1772,7 @@ QPDFObjectHandle::parse(
     QPDFTokenizer tokenizer;
     bool empty = false;
     QPDFObjectHandle result =
-        parse(input, object_description, tokenizer, empty, 0, context);
+        parse(input, object_description, tokenizer, empty, nullptr, context);
     size_t offset = QIntC::to_size(input->tell());
     while (offset < object_str.length()) {
         if (!isspace(object_str.at(offset))) {
@@ -1908,8 +1908,8 @@ QPDFObjectHandle::parseContentStream_data(
         tokenizer.readToken(input, "content", true);
         qpdf_offset_t offset = input->getLastOffset();
         input->seek(offset, SEEK_SET);
-        QPDFObjectHandle obj =
-            parseInternal(input, "content", tokenizer, empty, 0, context, true);
+        QPDFObjectHandle obj = parseInternal(
+            input, "content", tokenizer, empty, nullptr, context, true);
         if (!obj.isInitialized()) {
             // EOF
             break;
@@ -2185,7 +2185,7 @@ QPDFObjectHandle::parseInternal(
                     (olist.at(olist.size() - 1).isInteger()) &&
                     (!olist.at(olist.size() - 2).isIndirect()) &&
                     (olist.at(olist.size() - 2).isInteger())) {
-                    if (context == 0) {
+                    if (context == nullptr) {
                         QTC::TC(
                             "qpdf",
                             "QPDFObjectHandle indirect without context");
@@ -2661,7 +2661,7 @@ QPDFObjectHandle::newStream(
 QPDFObjectHandle
 QPDFObjectHandle::newStream(QPDF* qpdf)
 {
-    if (qpdf == 0) {
+    if (qpdf == nullptr) {
         throw std::runtime_error(
             "attempt to create stream in null qpdf object");
     }
@@ -2905,7 +2905,7 @@ QPDFObjectHandle::typeWarning(
 void
 QPDFObjectHandle::warnIfPossible(std::string const& warning)
 {
-    QPDF* context = 0;
+    QPDF* context = nullptr;
     std::string description;
     if (dereference() && obj->getDescription(context, description)) {
         warn(context, QPDFExc(qpdf_e_damaged_pdf, "", description, 0, warning));
@@ -3112,10 +3112,10 @@ QPDFObjectHandle::dereference()
         QPDF::Resolver::objectChanged(this->qpdf, getObjGen(), this->obj)) {
         this->obj = nullptr;
     }
-    if (this->obj.get() == 0) {
+    if (this->obj.get() == nullptr) {
         std::shared_ptr<QPDFObject> obj =
             QPDF::Resolver::resolve(this->qpdf, getObjGen());
-        if (obj.get() == 0) {
+        if (obj.get() == nullptr) {
             // QPDF::resolve never returns an uninitialized object, but
             // check just in case.
             this->obj = QPDF_Null::create();
diff --git a/libqpdf/QPDFOutlineDocumentHelper.cc b/libqpdf/QPDFOutlineDocumentHelper.cc
index 97189a23..4149ea1e 100644
--- a/libqpdf/QPDFOutlineDocumentHelper.cc
+++ b/libqpdf/QPDFOutlineDocumentHelper.cc
@@ -82,7 +82,7 @@ QPDFOutlineDocumentHelper::resolveNamedDest(QPDFObjectHandle name)
             result = this->m->dest_dict.getKey(name.getName());
         }
     } else if (name.isString()) {
-        if (0 == this->m->names_dest.get()) {
+        if (nullptr == this->m->names_dest.get()) {
             QPDFObjectHandle names = this->qpdf.getRoot().getKey("/Names");
             if (names.isDictionary()) {
                 QPDFObjectHandle dests = names.getKey("/Dests");
diff --git a/libqpdf/QPDFPageLabelDocumentHelper.cc b/libqpdf/QPDFPageLabelDocumentHelper.cc
index babfd5aa..805dc40f 100644
--- a/libqpdf/QPDFPageLabelDocumentHelper.cc
+++ b/libqpdf/QPDFPageLabelDocumentHelper.cc
@@ -16,7 +16,7 @@ QPDFPageLabelDocumentHelper::QPDFPageLabelDocumentHelper(QPDF& qpdf) :
 bool
 QPDFPageLabelDocumentHelper::hasPageLabels()
 {
-    return 0 != this->m->labels.get();
+    return nullptr != this->m->labels.get();
 }
 
 QPDFObjectHandle
diff --git a/libqpdf/QPDFTokenizer.cc b/libqpdf/QPDFTokenizer.cc
index d6467cc0..1726e1b9 100644
--- a/libqpdf/QPDFTokenizer.cc
+++ b/libqpdf/QPDFTokenizer.cc
@@ -17,7 +17,7 @@
 static bool
 is_delimiter(char ch)
 {
-    return (strchr(" \t\n\v\f\r()<>[]{}/%", ch) != 0);
+    return (strchr(" \t\n\v\f\r()<>[]{}/%", ch) != nullptr);
 }
 
 namespace
@@ -158,7 +158,7 @@ QPDFTokenizer::resolveLiteral()
                     num[0] = this->m->val.at(i + 1);
                     num[1] = this->m->val.at(i + 2);
                     num[2] = '\0';
-                    char ch2 = static_cast<char>(strtol(num, 0, 16));
+                    char ch2 = static_cast<char>(strtol(num, nullptr, 16));
                     if (ch2 == '\0') {
                         this->m->type = tt_bad;
                         QTC::TC("qpdf", "QPDFTokenizer null in name");
@@ -323,7 +323,7 @@ QPDFTokenizer::presentCharacter(char ch)
             // We've accumulated \ddd.  PDF Spec says to ignore
             // high-order overflow.
             this->m->val +=
-                static_cast<char>(strtol(this->m->bs_num_register, 0, 8));
+                static_cast<char>(strtol(this->m->bs_num_register, nullptr, 8));
             memset(
                 this->m->bs_num_register,
                 '\0',
@@ -447,7 +447,7 @@ QPDFTokenizer::presentCharacter(char ch)
             for (unsigned int i = 0; i < this->m->val.length(); i += 2) {
                 num[0] = this->m->val.at(i);
                 num[1] = this->m->val.at(i + 1);
-                char nch = static_cast<char>(strtol(num, 0, 16));
+                char nch = static_cast<char>(strtol(num, nullptr, 16));
                 nval += nch;
             }
             this->m->val = nval;
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 50ec9406..b227e95a 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -52,10 +52,10 @@ QPDFWriter::FunctionProgressReporter::reportProgress(int progress)
 QPDFWriter::Members::Members(QPDF& pdf) :
     pdf(pdf),
     filename("unspecified"),
-    file(0),
+    file(nullptr),
     close_file(false),
-    buffer_pipeline(0),
-    output_buffer(0),
+    buffer_pipeline(nullptr),
+    output_buffer(nullptr),
     normalize_content_set(false),
     normalize_content(false),
     compress_streams(true),
@@ -82,7 +82,7 @@ QPDFWriter::Members::Members(QPDF& pdf) :
     min_extension_level(0),
     forced_extension_level(0),
     encryption_dict_objid(0),
-    pipeline(0),
+    pipeline(nullptr),
     next_objid(1),
     cur_stream_length_id(0),
     cur_stream_length(0),
@@ -90,7 +90,7 @@ QPDFWriter::Members::Members(QPDF& pdf) :
     max_ostream_index(0),
     next_stack_id(0),
     deterministic_id(false),
-    md5_pipeline(0),
+    md5_pipeline(nullptr),
     did_write_setup(false),
     events_expected(0),
     events_seen(0),
@@ -128,9 +128,9 @@ void
 QPDFWriter::setOutputFilename(char const* filename)
 {
     char const* description = filename;
-    FILE* f = 0;
+    FILE* f = nullptr;
     bool close_file = false;
-    if (filename == 0) {
+    if (filename == nullptr) {
         description = "standard output";
         QTC::TC("qpdf", "QPDFWriter write to stdout");
         f = stdout;
@@ -169,7 +169,7 @@ Buffer*
 QPDFWriter::getBuffer()
 {
     Buffer* result = this->m->output_buffer;
-    this->m->output_buffer = 0;
+    this->m->output_buffer = nullptr;
     return result;
 }
 
@@ -1021,7 +1021,7 @@ QPDFWriter::writePad(int nspaces)
 Pipeline*
 QPDFWriter::pushPipeline(Pipeline* p)
 {
-    qpdf_assert_debug(dynamic_cast<Pl_Count*>(p) == 0);
+    qpdf_assert_debug(dynamic_cast<Pl_Count*>(p) == nullptr);
     this->m->pipeline_stack.push_back(p);
     return p;
 }
@@ -1066,10 +1066,10 @@ QPDFWriter::PipelinePopper::~PipelinePopper()
     qpdf_assert_debug(qw->m->pipeline->getIdentifier() == stack_id);
     delete qw->m->pipeline_stack.back();
     qw->m->pipeline_stack.pop_back();
-    while (dynamic_cast<Pl_Count*>(qw->m->pipeline_stack.back()) == 0) {
+    while (dynamic_cast<Pl_Count*>(qw->m->pipeline_stack.back()) == nullptr) {
         Pipeline* p = qw->m->pipeline_stack.back();
         if (dynamic_cast<Pl_MD5*>(p) == qw->m->md5_pipeline) {
-            qw->m->md5_pipeline = 0;
+            qw->m->md5_pipeline = nullptr;
         }
         qw->m->pipeline_stack.pop_back();
         Pl_Buffer* buf = dynamic_cast<Pl_Buffer*>(p);
@@ -1097,7 +1097,7 @@ void
 QPDFWriter::pushEncryptionFilter(PipelinePopper& pp)
 {
     if (this->m->encrypted && (!this->m->cur_data_key.empty())) {
-        Pipeline* p = 0;
+        Pipeline* p = nullptr;
         if (this->m->encrypt_use_aes) {
             p = new Pl_AES_PDF(
                 "aes stream encryption",
@@ -1135,7 +1135,7 @@ QPDFWriter::pushMD5Pipeline(PipelinePopper& pp)
                                " generation has already occurred.");
     }
     qpdf_assert_debug(this->m->deterministic_id);
-    qpdf_assert_debug(this->m->md5_pipeline == 0);
+    qpdf_assert_debug(this->m->md5_pipeline == nullptr);
     qpdf_assert_debug(this->m->pipeline->getCount() == 0);
     this->m->md5_pipeline = new Pl_MD5("qpdf md5", this->m->pipeline);
     this->m->md5_pipeline->persistAcrossFinish(true);
@@ -1148,7 +1148,7 @@ QPDFWriter::pushMD5Pipeline(PipelinePopper& pp)
 void
 QPDFWriter::computeDeterministicIDData()
 {
-    qpdf_assert_debug(this->m->md5_pipeline != 0);
+    qpdf_assert_debug(this->m->md5_pipeline != nullptr);
     qpdf_assert_debug(this->m->deterministic_id_data.empty());
     this->m->deterministic_id_data = this->m->md5_pipeline->getHexDigest();
     this->m->md5_pipeline->enable(false);
@@ -2455,10 +2455,10 @@ QPDFWriter::write()
     if (this->m->close_file) {
         fclose(this->m->file);
     }
-    this->m->file = 0;
+    this->m->file = nullptr;
     if (this->m->buffer_pipeline) {
         this->m->output_buffer = this->m->buffer_pipeline->getBuffer();
-        this->m->buffer_pipeline = 0;
+        this->m->buffer_pipeline = nullptr;
     }
     indicateProgress(false, true);
 }
@@ -2967,7 +2967,7 @@ QPDFWriter::writeLinearized()
 
     // Write file in two passes.  Part numbers refer to PDF spec 1.4.
 
-    FILE* lin_pass1_file = 0;
+    FILE* lin_pass1_file = nullptr;
     auto pp_pass1 = std::make_shared<PipelinePopper>(this);
     auto pp_md5 = std::make_shared<PipelinePopper>(this);
     for (int pass = 1; pass <= 2; ++pass) {
@@ -3203,13 +3203,13 @@ QPDFWriter::writeLinearized()
                     "QPDFWriter linearized deterministic ID",
                     need_xref_stream ? 0 : 1);
                 computeDeterministicIDData();
-                pp_md5 = 0;
-                qpdf_assert_debug(this->m->md5_pipeline == 0);
+                pp_md5 = nullptr;
+                qpdf_assert_debug(this->m->md5_pipeline == nullptr);
             }
 
             // Close first pass pipeline
             file_size = this->m->pipeline->getCount();
-            pp_pass1 = 0;
+            pp_pass1 = nullptr;
 
             // Save hint offset since it will be set to zero by
             // calling openObject.
@@ -3245,7 +3245,7 @@ QPDFWriter::writeLinearized()
                     "%% second_xref_end=%s\n",
                     QUtil::int_to_string(second_xref_end).c_str());
                 fclose(lin_pass1_file);
-                lin_pass1_file = 0;
+                lin_pass1_file = nullptr;
             }
         }
     }
@@ -3401,7 +3401,7 @@ QPDFWriter::writeStandard()
             "qpdf",
             "QPDFWriter standard deterministic ID",
             this->m->object_stream_to_objects.empty() ? 0 : 1);
-        pp_md5 = 0;
-        qpdf_assert_debug(this->m->md5_pipeline == 0);
+        pp_md5 = nullptr;
+        qpdf_assert_debug(this->m->md5_pipeline == nullptr);
     }
 }
diff --git a/libqpdf/QPDF_Dictionary.cc b/libqpdf/QPDF_Dictionary.cc
index be3c5dcd..60b2339f 100644
--- a/libqpdf/QPDF_Dictionary.cc
+++ b/libqpdf/QPDF_Dictionary.cc
@@ -87,7 +87,7 @@ QPDF_Dictionary::getKey(std::string const& key)
         return item->second;
     } else {
         QPDFObjectHandle null = QPDFObjectHandle::newNull();
-        QPDF* qpdf = 0;
+        QPDF* qpdf = nullptr;
         std::string description;
         if (getDescription(qpdf, description)) {
             null.setObjectDescription(
diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index 84965102..1b7f9461 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -169,7 +169,7 @@ QPDF_Stream::getFilterOnWrite() const
 void
 QPDF_Stream::releaseResolved()
 {
-    this->stream_provider = 0;
+    this->stream_provider = nullptr;
     QPDFObjectHandle::ReleaseResolver::releaseResolved(this->stream_dict);
 }
 
@@ -313,7 +313,7 @@ QPDF_Stream::setDescription(QPDF* qpdf, std::string const& description)
 void
 QPDF_Stream::setDictDescription()
 {
-    QPDF* qpdf = 0;
+    QPDF* qpdf = nullptr;
     std::string description;
     if ((!this->stream_dict.hasObjectDescription()) &&
         getDescription(qpdf, description)) {
@@ -547,7 +547,7 @@ QPDF_Stream::pipeStreamData(
                                           : 3);
     }
 
-    if (pipeline == 0) {
+    if (pipeline == nullptr) {
         QTC::TC("qpdf", "QPDF_Stream pipeStreamData with null pipeline");
         // Return value is whether we can filter in this case.
         return filter;
@@ -693,7 +693,7 @@ QPDF_Stream::replaceStreamData(
     QPDFObjectHandle const& decode_parms)
 {
     this->stream_data = data;
-    this->stream_provider = 0;
+    this->stream_provider = nullptr;
     replaceFilterData(filter, decode_parms, data->getSize());
 }
 
@@ -704,7 +704,7 @@ QPDF_Stream::replaceStreamData(
     QPDFObjectHandle const& decode_parms)
 {
     this->stream_provider = provider;
-    this->stream_data = 0;
+    this->stream_data = nullptr;
     replaceFilterData(filter, decode_parms, 0);
 }
 
diff --git a/libqpdf/QPDF_encryption.cc b/libqpdf/QPDF_encryption.cc
index 8c35b992..266907a8 100644
--- a/libqpdf/QPDF_encryption.cc
+++ b/libqpdf/QPDF_encryption.cc
@@ -149,8 +149,8 @@ QPDF::trim_user_password(std::string& user_password)
     }
 
     char const* p1 = cstr;
-    char const* p2 = 0;
-    while ((p2 = strchr(p1, '\x28')) != 0) {
+    char const* p2 = nullptr;
+    while ((p2 = strchr(p1, '\x28')) != nullptr) {
         size_t idx = toS(p2 - cstr);
         if (memcmp(p2, padding_string, len - idx) == 0) {
             user_password = user_password.substr(0, idx);
@@ -218,7 +218,7 @@ process_with_aes(
     std::string const& data,
     size_t outlength = 0,
     unsigned int repetitions = 1,
-    unsigned char const* iv = 0,
+    unsigned char const* iv = nullptr,
     size_t iv_length = 0)
 {
     Pl_Buffer buffer("buffer");
diff --git a/libqpdf/QPDF_linearization.cc b/libqpdf/QPDF_linearization.cc
index 64805f58..f89ed188 100644
--- a/libqpdf/QPDF_linearization.cc
+++ b/libqpdf/QPDF_linearization.cc
@@ -542,7 +542,7 @@ QPDF::checkLinearizationInternal()
 
     // T: offset of whitespace character preceding xref entry for object 0
     this->m->file->seek(p.xref_zero_offset, SEEK_SET);
-    while (1) {
+    while (true) {
         char ch;
         this->m->file->read(&ch, 1);
         if (!((ch == ' ') || (ch == '\r') || (ch == '\n'))) {
diff --git a/libqpdf/QUtil.cc b/libqpdf/QUtil.cc
index 7a5d3caf..4e58aaf7 100644
--- a/libqpdf/QUtil.cc
+++ b/libqpdf/QUtil.cc
@@ -396,7 +396,7 @@ QUtil::string_to_ll(char const* str)
 #ifdef _MSC_VER
     long long result = _strtoi64(str, 0, 10);
 #else
-    long long result = strtoll(str, 0, 10);
+    long long result = strtoll(str, nullptr, 10);
 #endif
     if (errno == ERANGE) {
         throw std::range_error(
@@ -430,7 +430,7 @@ QUtil::string_to_ull(char const* str)
 #ifdef _MSC_VER
     unsigned long long result = _strtoui64(str, 0, 10);
 #else
-    unsigned long long result = strtoull(str, 0, 10);
+    unsigned long long result = strtoull(str, nullptr, 10);
 #endif
     if (errno == ERANGE) {
         throw std::runtime_error(
@@ -512,7 +512,7 @@ win_convert_filename(char const* filename)
 FILE*
 QUtil::safe_fopen(char const* filename, char const* mode)
 {
-    FILE* f = 0;
+    FILE* f = nullptr;
 #ifdef _WIN32
     std::shared_ptr<wchar_t> wfilenamep = win_convert_filename(filename);
     wchar_t* wfilename = wfilenamep.get();
@@ -543,7 +543,7 @@ QUtil::safe_fopen(char const* filename, char const* mode)
 FILE*
 QUtil::fopen_wrapper(std::string const& description, FILE* f)
 {
-    if (f == 0) {
+    if (f == nullptr) {
         throw_system_error(description);
     }
     return f;
@@ -599,7 +599,7 @@ QUtil::tell(FILE* stream)
 bool
 QUtil::same_file(char const* name1, char const* name2)
 {
-    if ((name1 == 0) || (strlen(name1) == 0) || (name2 == 0) ||
+    if ((name1 == nullptr) || (strlen(name1) == 0) || (name2 == nullptr) ||
         (strlen(name2) == 0)) {
         return false;
     }
@@ -834,7 +834,7 @@ QUtil::setLineBuf(FILE* f)
 char*
 QUtil::getWhoami(char* argv0)
 {
-    char* whoami = 0;
+    char* whoami = nullptr;
     if (((whoami = strrchr(argv0, '/')) == NULL) &&
         ((whoami = strrchr(argv0, '\\')) == NULL)) {
         whoami = argv0;
@@ -875,7 +875,7 @@ QUtil::get_env(std::string const& var, std::string* value)
 # endif
 #else
     char* p = getenv(var.c_str());
-    if (p == 0) {
+    if (p == nullptr) {
         return false;
     }
     if (value) {
@@ -908,7 +908,7 @@ QUtil::get_current_time()
     ULONGLONG now = uinow.QuadPart;
     return static_cast<time_t>((now / 10000000ULL) - 11644473600ULL);
 #else
-    return time(0);
+    return time(nullptr);
 #endif
 }
 
@@ -931,7 +931,7 @@ QUtil::get_current_qpdf_time()
         static_cast<int>(tzinfo.Bias));
 #else
     struct tm ltime;
-    time_t now = time(0);
+    time_t now = time(nullptr);
     tzset();
 # ifdef HAVE_LOCALTIME_R
     localtime_r(&now, &ltime);
@@ -1155,7 +1155,7 @@ namespace
 
 RandomDataProviderProvider::RandomDataProviderProvider() :
     default_provider(CryptoRandomDataProvider::getInstance()),
-    current_provider(0)
+    current_provider(nullptr)
 {
     this->current_provider = default_provider;
 }
@@ -1210,13 +1210,13 @@ QUtil::random()
 bool
 QUtil::is_hex_digit(char ch)
 {
-    return (ch && (strchr("0123456789abcdefABCDEF", ch) != 0));
+    return (ch && (strchr("0123456789abcdefABCDEF", ch) != nullptr));
 }
 
 bool
 QUtil::is_space(char ch)
 {
-    return (ch && (strchr(" \f\n\r\t\v", ch) != 0));
+    return (ch && (strchr(" \f\n\r\t\v", ch) != nullptr));
 }
 
 bool
@@ -1332,10 +1332,10 @@ QUtil::read_lines_from_file(
     std::list<std::string>& lines,
     bool preserve_eol)
 {
-    std::string* buf = 0;
+    std::string* buf = nullptr;
     char c;
     while (next_char(c)) {
-        if (buf == 0) {
+        if (buf == nullptr) {
             lines.push_back("");
             buf = &(lines.back());
             buf->reserve(80);
@@ -1354,7 +1354,7 @@ QUtil::read_lines_from_file(
                     buf->erase(buf->length() - 1);
                 }
             }
-            buf = 0;
+            buf = nullptr;
         } else {
             buf->append(1, c);
         }
@@ -1471,7 +1471,7 @@ QUtil::parse_numrange(char const* range, int max)
             }
         }
 
-        p = 0;
+        p = nullptr;
         for (size_t i = 0; i < work.size(); i += 2) {
             int num = work.at(i);
             // max == 0 means we don't know the max and are just
@@ -1990,7 +1990,7 @@ call_main_from_wmain(
         new_argv[i] = utf8_argv.at(i).get();
     }
     argc = QIntC::to_int(utf8_argv.size());
-    new_argv[argc] = 0;
+    new_argv[argc] = nullptr;
     return realmain(argc, new_argv);
 }
 
diff --git a/libqpdf/qpdf-c.cc b/libqpdf/qpdf-c.cc
index bde0ac72..390699db 100644
--- a/libqpdf/qpdf-c.cc
+++ b/libqpdf/qpdf-c.cc
@@ -164,7 +164,7 @@ qpdf_cleanup(qpdf_data* qpdf)
             << (*qpdf)->error->what() << "\n";
     }
     delete *qpdf;
-    *qpdf = 0;
+    *qpdf = nullptr;
 }
 
 size_t
@@ -203,11 +203,11 @@ qpdf_get_error(qpdf_data qpdf)
 {
     if (qpdf->error.get()) {
         qpdf->tmp_error.exc = qpdf->error;
-        qpdf->error = 0;
+        qpdf->error = nullptr;
         QTC::TC("qpdf", "qpdf-c qpdf_get_error returned error");
         return &qpdf->tmp_error;
     } else {
-        return 0;
+        return nullptr;
     }
 }
 
@@ -220,14 +220,14 @@ qpdf_next_warning(qpdf_data qpdf)
         QTC::TC("qpdf", "qpdf-c qpdf_next_warning returned warning");
         return &qpdf->tmp_error;
     } else {
-        return 0;
+        return nullptr;
     }
 }
 
 char const*
 qpdf_get_error_full_text(qpdf_data qpdf, qpdf_error e)
 {
-    if (e == 0) {
+    if (e == nullptr) {
         return "";
     }
     return e->exc->what();
@@ -236,7 +236,7 @@ qpdf_get_error_full_text(qpdf_data qpdf, qpdf_error e)
 enum qpdf_error_code_e
 qpdf_get_error_code(qpdf_data qpdf, qpdf_error e)
 {
-    if (e == 0) {
+    if (e == nullptr) {
         return qpdf_e_success;
     }
     return e->exc->getErrorCode();
@@ -245,7 +245,7 @@ qpdf_get_error_code(qpdf_data qpdf, qpdf_error e)
 char const*
 qpdf_get_error_filename(qpdf_data qpdf, qpdf_error e)
 {
-    if (e == 0) {
+    if (e == nullptr) {
         return "";
     }
     return e->exc->getFilename().c_str();
@@ -254,7 +254,7 @@ qpdf_get_error_filename(qpdf_data qpdf, qpdf_error e)
 unsigned long long
 qpdf_get_error_file_position(qpdf_data qpdf, qpdf_error e)
 {
-    if (e == 0) {
+    if (e == nullptr) {
         return 0;
     }
     return QIntC::to_ulonglong(e->exc->getFilePosition());
@@ -263,7 +263,7 @@ qpdf_get_error_file_position(qpdf_data qpdf, qpdf_error e)
 char const*
 qpdf_get_error_message_detail(qpdf_data qpdf, qpdf_error e)
 {
-    if (e == 0) {
+    if (e == nullptr) {
         return "";
     }
     return e->exc->getMessageDetail().c_str();
@@ -371,7 +371,7 @@ qpdf_get_user_password(qpdf_data qpdf)
 char const*
 qpdf_get_info_key(qpdf_data qpdf, char const* key)
 {
-    char const* result = 0;
+    char const* result = nullptr;
     QPDFObjectHandle trailer = qpdf->qpdf->getTrailer();
     if (trailer.hasKey("/Info")) {
         QPDFObjectHandle info = trailer.getKey("/Info");
@@ -383,14 +383,14 @@ qpdf_get_info_key(qpdf_data qpdf, char const* key)
             }
         }
     }
-    QTC::TC("qpdf", "qpdf-c get_info_key", (result == 0 ? 0 : 1));
+    QTC::TC("qpdf", "qpdf-c get_info_key", (result == nullptr ? 0 : 1));
     return result;
 }
 
 void
 qpdf_set_info_key(qpdf_data qpdf, char const* key, char const* value)
 {
-    if ((key == 0) || (std::strlen(key) == 0) || (key[0] != '/')) {
+    if ((key == nullptr) || (std::strlen(key) == 0) || (key[0] != '/')) {
         return;
     }
     QPDFObjectHandle value_object;
@@ -498,11 +498,11 @@ qpdf_init_write_internal(qpdf_data qpdf)
 {
     if (qpdf->qpdf_writer.get()) {
         QTC::TC("qpdf", "qpdf-c called qpdf_init_write multiple times");
-        qpdf->qpdf_writer = 0;
+        qpdf->qpdf_writer = nullptr;
         if (qpdf->output_buffer.get()) {
-            qpdf->output_buffer = 0;
+            qpdf->output_buffer = nullptr;
             qpdf->write_memory = false;
-            qpdf->filename = 0;
+            qpdf->filename = nullptr;
         }
     }
 }
@@ -530,7 +530,7 @@ qpdf_init_write_memory(qpdf_data qpdf)
 static void
 qpdf_get_buffer_internal(qpdf_data qpdf)
 {
-    if (qpdf->write_memory && (qpdf->output_buffer == 0)) {
+    if (qpdf->write_memory && (qpdf->output_buffer == nullptr)) {
         qpdf->output_buffer = qpdf->qpdf_writer->getBufferSharedPointer();
     }
 }
@@ -549,7 +549,7 @@ qpdf_get_buffer_length(qpdf_data qpdf)
 unsigned char const*
 qpdf_get_buffer(qpdf_data qpdf)
 {
-    unsigned char const* result = 0;
+    unsigned char const* result = nullptr;
     qpdf_get_buffer_internal(qpdf);
     if (qpdf->output_buffer.get()) {
         result = qpdf->output_buffer->getBuffer();