Convert a string to an integer

Question

Brian · Accepted Answer

Not exactly super, but should do for a whiteboard:

int
myatoi (char *str)
{
    int retval;
    int sign;

    sign = 1;
    if (*str == '-') {
        sign = -1;
        str++;
    }

    retval = 0;
    while (*str) {
       retval *= 10;
       retval += *str - '0';
       str++;
    }
    return (retval * sign);
}

Further... · Answer

The pointer is a char pointer, so the loop (and the sign check) are on a character by character basis.

Sigiloso · Answer

Brian is right, he is using C char pointers, and can compare a character at a time. This is not Java, this does work.

Mike · Answer

int.Parse(str) hah.

But in all seriousness, the aforementioned solution is good.

Sigiloso · Answer

Bug,

The check is just for the first character of the string - your version will not even compile...

Bug · Answer

I think, there is bug at statement
if (*str == '-1') ........ what if str = "-1234"

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