Api function
#include <idn2.h>
const char * idn2_check_version(const char * req_version);
version string to compare with, or NULL.
Check IDN2 library version. This function can also be used to read out the version of the library code used. See IDN2_VERSION for a suitable req_version string, it corresponds to the idn2.h header file version. Normally these two version numbers match, but if you are using an application built against an older libidn2 with a newer libidn2 shared library they will be different.
Check that the version of the library is at minimum the one given as a string in req_version and return the actual version string of the library; return NULL if the condition is not met. If NULL is passed to this function no check is done and only the version string is returned.
The full documentation for libidn2 is maintained as a Texinfo manual. If the info and libidn2 programs are properly installed at your site, the command
info libidn2
should give you access to the complete manual.