@deftypefun {int} {gnutls_x509_crt_export} (gnutls_x509_crt_t @var{cert}, gnutls_x509_crt_fmt_t @var{format}, void * @var{output_data}, size_t * @var{output_data_size}) @var{cert}: Holds the certificate @var{format}: the format of output params. One of PEM or DER. @var{output_data}: will contain a certificate PEM or DER encoded @var{output_data_size}: holds the size of output_data (and will be replaced by the actual size of parameters) This function will export the certificate to DER or PEM format. If the buffer provided is not long enough to hold the output, then *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will be returned. If the structure is PEM encoded, it will have a header of "BEGIN CERTIFICATE". @strong{Returns:} In case of failure a negative error code will be returned, and 0 on success. @end deftypefun