OS2

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <regex.h>
#include <libc.h>


int replaceInText(const char *pattern, char **str, const char *replace)
{
    char *s = *str;
    regex_t reg;
    char *new;
    const char *p;

    if (regcomp(&reg, pattern, REG_EXTENDED))
        return -1;

    size_t nm = reg.re_nsub;
    regmatch_t pmatch[nm + 1];

    while (!regexec(&reg, s, nm + 1, pmatch, REG_NOTBOL))
    {
        new = (char *) malloc(strlen(*str) + strlen(replace));
        strncat(new, *str, s - *str);
        p = replace;
        strncat(new, s, pmatch[0].rm_so);
        strcat(new, p);
        unsigned int off = strlen(new);
        strcat(new, s + pmatch[0].rm_eo);
        *str = (char *) malloc(strlen(new) + 1);
        strcpy(*str, new);
        s = *str + off;
        free(new);
    }
    regfree(&reg);
    *str = (char *) realloc(*str, strlen(*str) + 1);

    return 0;
}

int main(int argc, char **argv)
{

    char *regex = argv[1];
    char *text = argv[2];
    char *replacement = argv[3];
    replaceInText(regex, &text, replacement);
    printf("%s", text);

    return 0;
}