Searching the Berkeley Unix way means searching in a string
starting at its first character and trying successive positions within
it to find a match. Once you’ve compiled a pattern using
(see BSD Regular Expression Compiling), you can ask Regex
to search for that pattern in a string using:
int re_exec (char *string)
string is the address of the null-terminated string in which you want to search.
re_exec returns either 1 for success or 0 for failure. It
automatically uses a GNU fastmap (see Searching with Fastmaps).