[garaetjjte]

Possibly OP meant dlopen/dlsym on itself? But that's a stretch, and not really language feature...

[lights0123]

And functions aren't guaranteed to be included in the binary unless you pass additional compiler flags with that strategy.

[_3u10]

Very few things are guaranteed in C. If you want to guarantee the function exists let the operating system look up the function names by string for you.