Once you have compiled a regular expression, as described in POSIX Regular Expression Compilation, you can match it against strings using
regexec. A match anywhere inside the string counts as success,
unless the regular expression contains anchor characters (‘^’ or
Preliminary: | MT-Safe locale | AS-Unsafe corrupt heap lock dlopen | AC-Unsafe corrupt lock mem fd | See POSIX Safety Concepts.
This function tries to match the compiled regular expression
*compiled against string.
0 if the regular expression matches;
otherwise, it returns a nonzero value. See the table below for
what nonzero values mean. You can use
regerror to produce an
error message string describing the reason for a nonzero value;
see POSIX Regexp Matching Cleanup.
The argument eflags is a word of bit flags that enable various options.
If you want to get information about what part of string actually
matched the regular expression or its subexpressions, use the arguments
matchptr and nmatch. Otherwise, pass
NULL for matchptr. See Match Results with Subexpressions.
You must match the regular expression with the same set of current locales that were in effect when you compiled the regular expression.
regexec accepts the following flags in the
Do not regard the beginning of the specified string as the beginning of a line; more generally, don’t make any assumptions about what text might precede it.
Do not regard the end of the specified string as the end of a line; more generally, don’t make any assumptions about what text might follow it.
Here are the possible nonzero values that
regexec can return: