This example compiles an expression and matches a string against it. The first substring uses the full pattern. The second substring uses the sub-expression inside the full pattern.
#include <regex.h> #include <stdio.h> #include <stdlib.h>
int main(void)
{
regex_t preg;
char *string = "a very simple simple simple string";
char *pattern = "\\(sim[a-z]le\\) \\1";
int rc;
size_t nmatch = 2;
regmatch_t pmatch[2];
if (0 != (rc = regcomp(&preg, pattern, 0))) {
printf("regcomp() failed, returning nonzero (%d)\n", rc);
exit(EXIT_FAILURE);
}
if (0 != (rc = regexec(&preg, string, nmatch, pmatch, 0))) {
printf("Failed to match '%s' with '%s',returning %d.\n",
string, pattern, rc);
}
else {
printf("With the whole expression, "
"a matched substring \"%.*s\" is found at position %d to %d.\n",
pmatch[0].rm_eo - pmatch[0].rm_so, &string[pmatch[0].rm_so],
pmatch[0].rm_so, pmatch[0].rm_eo - 1);
printf("With the sub-expression, "
"a matched substring \"%.*s\" is found at position %d to %d.\n",
pmatch[1].rm_eo - pmatch[1].rm_so, &string[pmatch[1].rm_so],
pmatch[1].rm_so, pmatch[1].rm_eo - 1);
}
regfree(&preg);
return 0;
/****************************************************************************
The output should be similar to :
With the whole expression, a matched substring "simple simple" is found
at position 7 to 19.
With the sub-expression, a matched substring "simple" is found
at position 7 to 12.
****************************************************************************/
}