This file is an update to the "robert_2.c" file located here: https://github.com/regehr/str2long_contest This is a contest for parsing integers with no integer overflows. The performance tests use mostly invalid input, which skews the performance results. My "robert_2.c" code is half as fast as the fastest "yang_2.c" code. That's because Yang in…

robert_3.c

#include "str2long.h"

long str2long_robert_3(const char *str)
{
    long result = 0;
    int i;

    if (str[0] == '-') {
        if (str[1] == '\0')
            error = 1;
        for (i=1; str[i]=='0'; i++)
            ;
        for (; str[i]; i++) {
            int c = str[i];

            if (c < '0' || '9' < c) {
                error = 1;
                return 0;
            } else if (result < LONG_MIN/10) {
                error = 1;
                return 0;
            } else if (result * 10 < (LONG_MIN + (c - '0'))) {
                error = 1;
                return 0;
            } else
                result = result * 10 - (c - '0');
        }
    } else {
        if (str[0] == '\0')
            error = 1;

        for (i=0; str[i]=='0'; i++)
            ;
        for (; str[i]; i++) {
            int c = str[i];

            if (c < '0' || '9' < c) {
                error = 1;
                return 0;
            } else if (result > LONG_MAX/10) {
                error = 1;
                return 0;
            } else if (result * 10 > (LONG_MAX - (c - '0'))) {
                error = 1;
                return 0;
            } else
                result = result * 10 + (c - '0');
        }
    }
    return result;
}