Add actual example programs from prior examples, start documentation updates.

examples/pdfioinfo.c

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+//
+// PDF metadata example for PDFio.
+//
+// Copyright © 2023-2024 by Michael R Sweet.
+//
+// Licensed under Apache License v2.0.  See the file "LICENSE" for more
+// information.
+//
+// Usage:
+//
+//   ./pdfioinfo FILENAME.pdf
+//
+
+#include <pdfio.h>
+#include <time.h>
+
+
+//
+// 'main()' - Open a PDF file and show its metadata.
+//
+
+int					// O - Exit status
+main(int  argc,				// I - Number of command-line arguments
+     char *argv[])			// Command-line arguments
+{
+  const char	*filename;		// PDF filename
+  pdfio_file_t	*pdf;			// PDF file
+  time_t	creation_date;		// Creation date
+  struct tm	*creation_tm;		// Creation date/time information
+  char		creation_text[256];	// Creation date/time as a string
+
+
+  // Get the filename from the command-line...
+  if (argc != 2)
+  {
+    fputs("Usage: ./pdfioinfo FILENAME.pdf\n", stderr);
+    return (1);
+  }
+
+  filename = argv[1];
+
+  // Open the PDF file with the default callbacks...
+  pdf = pdfioFileOpen(filename, /*password_cb*/NULL,
+                      /*password_cbdata*/NULL, /*error_cb*/NULL,
+                      /*error_cbdata*/NULL);
+  if (pdf == NULL)
+    return (1);
+
+  // Get the creation date and convert to a string...
+  creation_date = pdfioFileGetCreationDate(pdf);
+  creation_tm   = localtime(&creation_date);
+  strftime(creation_text, sizeof(creation_text), "%c", creation_tm);
+
+  // Print file information to stdout...
+  printf("%s:\n", filename);
+  printf("         Title: %s\n", pdfioFileGetTitle(pdf));
+  printf("        Author: %s\n", pdfioFileGetAuthor(pdf));
+  printf("    Created On: %s\n", creation_text);
+  printf("  Number Pages: %u\n", (unsigned)pdfioFileGetNumPages(pdf));
+
+  // Close the PDF file...
+  pdfioFileClose(pdf);
+
+  return (0);
+}