55c
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <regex.h>
#include <rl.h>

#define REGEXEC

int main(void)
{
    regex_t reg;
    regmatch_t pmatch[1];
    char rbuf[256];
    char teststr[82], *p;
    char regexpr[82] = "";
    int r;
#ifndef REGEXEC
    char *rs;
#endif

    if (! (p = rl_gets("Enter a test string: ", NULL)))
	exit(0);
    strcpy(teststr, p);

    while(1) {
	if (! (p = rl_gets("Enter a regular expression: ", regexpr)))
	    exit(0);
	if(! strlen(p)) {
	    if (! (p = rl_gets("Enter a test string: ", NULL)))
		exit(0);
	    if(! strlen(p))
		break;
	    strcpy(teststr, p);
	    continue;
	}

	strcpy(regexpr, p);

#ifdef REGEXEC
	if((r = regcomp(&reg, regexpr, REG_EXTENDED))) {
	    fprintf(stderr, "%d\n", r);
	    regerror(r, &reg, rbuf, 256);
	    printf("%s\n", rbuf);
	    regfree(&reg);
	    continue;
	}

	if(! (r = regexec(&reg, teststr, 1, pmatch, 0))) {
	    printf("Matches!!\n");
	    printf("Offset: %d\n", (int)pmatch[0].rm_so);
	} else {
	    regerror(r, &reg, rbuf, 256);
	    printf("%s\n", rbuf);
	}

	regfree(&reg);
#else
	if((rs = re_comp(regexpr)) != NULL) {
	    printf("%s\n", rs);
	    continue;
	}

	if((r = re_exec(teststr)) == 1)
	    printf("Matches!!\n");
	else
	    printf("No match\n");
#endif
    }

    return 0;
}
.

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