This program loads a file hello.pdf from disk and writes out a document with the original included three times. Note the use of cpdf_startup, cpdf_lastError and cpdf_clearError.
#include <stdbool.h>
#include "cpdflibwrapper.h"
int main (int argc, char ** argv)
{
/* Initialise cpdf */
cpdf_startup(argv);
/* We will take the input hello.pdf and repeat it three times */
int mergepdf = cpdf_fromFile("hello.pdf", "");
/* Check the error state */
if (cpdf_lastError) return 1;
/* Clear the error state */
cpdf_clearError();
/* The array of PDFs to merge */
int pdfs[] = {mergepdf, mergepdf, mergepdf};
/* Merge them */
int merged = cpdf_mergeSimple(pdfs, 3);
if (cpdf_lastError) return 1;
cpdf_clearError();
/* Write output */
cpdf_toFile(merged, "merged.pdf", false, false);
if (cpdf_lastError) return 1;
return 0;
}