Best way to scan string for a number?

[SneakySnake]

My string input can either be "-c123" or "-c 123".

What's the best way to scan the string to get the number out?

[qny]

If you don't need tight control, try atoi().
If you want tighter control of errors, prefer strtol().

Read the function descriptions!!!

char input1[] = "-c123";
char input2[] = "-c 123";
int val1atoi = atoi(input1 + 2);
int val2atoi = atoi(input2 + 2);

char *err;
errno = 0; int val1strtol = strtol(input1 + 2, &err, 10); /* test *err, val1strtol, and errno */
errno = 0; int val2strtol = strtol(input2 + 2, &err, 10); /* test *err, val2strtol, and errno */

You can also use sscanf() withy a littel more control than atoi() and a little less than strtol() ...

char input[] = "-c 123";
int val;
if (sscanf(input, "-c%d", &val) != 1) /* error */;

All 3 funtions above properly ignore whitespace.

[SneakySnake]

thanks a ton. I was messing around with sscanf() but didn't really wrap my head around it.