parse_int.c

int parse_int(const char *str, bool *overflow) {
    int pos = 1;
    if (*str == '-') {
        pos = 0;
        str++;
    }
    int num = 0;
    *overflow = false;
    while (isdigit(*str)) {
        int d = *str - '0';
        if (num < (INT_MIN + d) / 10) {
            *overflow = true;
            num = INT_MIN;
            break;
        }
        num = 10 * num - d;
        *str++;
    }
    if (pos) {
        if (num < -INT_MAX) {
            *overflow = true;
            num = INT_MAX;
        } else {
            num = -num;
        }
    }
    return num;
}