man byte_chr (3): search for a byte in a string

SYNTAX

#include <byte.h>

size_t byte_chr(const char *haystack,size_t len,char needle);

byte_chr returns the smallest integer i between 0 and len-1 inclusive such that one[i] equals needle.

If no such integer exists, byte_chr returns len.

byte_chr may read all bytes one[0], one[1], ..., one[len-1], even if not all the bytes are relevant to the answer.