From d7a364b882be44c93dc4a843bcca2ae63e805c2c Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sat, 16 Dec 2023 09:46:44 -0500
Subject: Allow regular C++ functions to interoperate with the C API

---
 examples/extend-c-api.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 examples/extend-c-api.c

(limited to 'examples/extend-c-api.c')

diff --git a/examples/extend-c-api.c b/examples/extend-c-api.c
new file mode 100644
index 00000000..aa603845
--- /dev/null
+++ b/examples/extend-c-api.c
@@ -0,0 +1,67 @@
+/*
+ * This is an example of how to write C++ functions and make them usable with the qpdf C API. It
+ * consists of three files:
+ * - extend-c-api.h -- a plain C header file
+ * - extend-c-api.c -- a C program that calls the function
+ * - extend-c-api.cc -- a C++ file that implements the function
+ */
+
+#include "extend-c-api.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char const* whoami = 0;
+
+static void
+usage()
+{
+    fprintf(stderr, "Usage: %s infile\n", whoami);
+    exit(2);
+}
+
+int
+main(int argc, char* argv[])
+{
+    char* infile = NULL;
+    qpdf_data qpdf = qpdf_init();
+    int warnings = 0;
+    int errors = 0;
+    char* p = NULL;
+
+    if ((p = strrchr(argv[0], '/')) != NULL) {
+        whoami = p + 1;
+    } else if ((p = strrchr(argv[0], '\\')) != NULL) {
+        whoami = p + 1;
+    } else {
+        whoami = argv[0];
+    }
+
+    if (argc != 2) {
+        usage();
+    }
+
+    infile = argv[1];
+
+    if ((qpdf_read(qpdf, infile, NULL) & QPDF_ERRORS) == 0) {
+        int npages;
+        if ((num_pages(qpdf, &npages) & QPDF_ERRORS) == 0) {
+            printf("num pages = %d\n", npages);
+        }
+    }
+    if (qpdf_more_warnings(qpdf)) {
+        warnings = 1;
+    }
+    if (qpdf_has_error(qpdf)) {
+        errors = 1;
+        printf("error: %s\n", qpdf_get_error_full_text(qpdf, qpdf_get_error(qpdf)));
+    }
+    qpdf_cleanup(&qpdf);
+    if (errors) {
+        return 2;
+    } else if (warnings) {
+        return 3;
+    }
+
+    return 0;
+}
-- 
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