libssh2_version - Man Page

#include <libssh2.h>

const char *
libssh2_version(int required_version);

If required_version is lower than or equal to the version number of the libssh2 in use, the version number of libssh2 is returned as a pointer to a zero terminated string.

The required_version should be the version number as constructed by the LIBSSH2_VERSION_NUM define in the libssh2.h public header file, which is a 24 bit number in the 0xMMmmpp format. MM for major, mm for minor and pp for patch number.

The version number of libssh2 is returned as a pointer to a zero terminated string or NULL if the required_version is not fulfilled.

To make sure you run with the correct libssh2 version:

if(!libssh2_version(LIBSSH2_VERSION_NUM)) {
  fprintf(stderr, "Runtime libssh2 version too old!");
  exit(1);
}

Unconditionally get the version number:

printf("libssh2 version: %s", libssh2_version(0));

This function was added in libssh2 1.1, in previous versions there way no way to extract this info in run-time.