/* Output every line of standard input that matches the regular expression. */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <regex.h>

int main(int argc, char **argv)
{
	regex_t expression;
	const int error = regcomp(&expression, "^moe[0-9]", 0);
	char line[1024];

	if (error != 0) {
		const size_t length = regerror(error, &expression, NULL, 0);
		if (length == 0) {
			fprintf(stderr, "%s: regerror not implemented\n", argv[0]);
		} else {
			char *const p = malloc(length);
			if (p == NULL) {
				fprintf(stderr, "%s: can't malloc space for error message\n",
					argv[0]);
			} else {
				regerror(error, &expression, p, length);
				fprintf(stderr, "%s: %s\n", argv[0], p);
				free(p);
			}
		}
		return EXIT_FAILURE;
	}

	while (fgets(line, sizeof line, stdin) != NULL) {
		if (regexec(&expression, line, 0, NULL, 0) == 0) {
			fputs(line, stdout);
		}
	}

	regfree(&expression);
	return EXIT_SUCCESS;
}