#include <fontconfig.h>
const FcChar8 * FcCacheSubdir(const FcCache *cache, inti);
const FcChar8 * FcCacheSubdir
The set of subdirectories stored in a cache file are indexed by this function, i should range from 0 to n-1, where n is the return value from FcCacheNumSubdir.
Fontconfig version 2.8.0