FcCharSetMerge (3) - Linux Manuals
FcCharSetMerge: Merge charsets
NAME
FcCharSetMerge - Merge charsets
SYNOPSIS
#include <fontconfig/fontconfig.h>
FcBool FcCharSetMerge (FcCharSet *a, const FcCharSet *b, FcBool *changed);
DESCRIPTION
Adds all chars in b to a. In other words, this is an in-place version of FcCharSetUnion. If changed is not NULL, then it returns whether any new chars from b were added to a. Returns FcFalse on failure, either when a is a constant set or from running out of memory.