Parse a char string into an INT C programming

Question

I'm trying to parse a char string into an INT.

If I had...

unsigned char color[] = "255"

And wanted to parse this into an INT. How would I go about doing this?

I tried...

unsigned char *split;

split = strtok(color," ,.-");
while(split != NULL)
{
    split = strok(NULL, " ,.-);
}

This just gives me the value 255 for split now.

I feel like I need something like...

int y = split - '0';   //but this makes an INT pointer without a cast

fluter · Accepted Answer · 2016-05-05 06:52:56Z

5

To convert a string to integer, call strtol:

char color[] = "255";
long n;
char *end = NULL;
n = strtol(color, &end, 10);
if (*end == '\0') {
    // convert was successful
    // n is the result
}

edited May 5, 2016 at 6:52

answered May 5, 2016 at 6:42

fluter

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1 Comment

fluter Over a year ago

@user3622460 glad to know it helps.

ad3angel1s · Accepted Answer · 2016-05-05 08:25:52Z

0

If you want to convert without calling strtol you can scan the color array and compare each char against '0' to get the corresponding numeric value, then add the result properly multiplied by a power of 10, i.e.

int i = 0, strlen = 0, result = 0;
while (color[i++]) strlen++;
for (i = 0; i<strlen; i++)
{
    result += (color[i] - '0')*pow(10,strlen-1-i);
}

answered May 5, 2016 at 8:25

ad3angel1s

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1 Comment

Jongware Over a year ago

I don't get the impression "without strtol" was OPs idea.

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