Question

Is there any API to check if any number exceeds it’s range?

My number is stored as string. char *ptr = "123456789"

API should do: int a = api(ptr, long) if a==-1 suppose value exceeds.

Please note: We can’t parse the string and check because it will automatically wrap it to the other side, and make it within the range.

Thanks in advance

Answer 1

Please checkout strtol and strtoul.

See this example:

#include <stdlib.h>
#include <errno.h>
#include <limits.h>
int main (int argc, char const* argv[])
{
    char a[] = "123";
    char c[] = "123134123412341234";
    long b, d;
    errno = 0;
    b = strtol(a, NULL, 10);
    if((b == LONG_MAX || b == LONG_MIN) && errno == ERANGE ){
        printf("%s Out of range\n", a);
    }
    errno = 0;
    d = strtol(c, NULL, 10);
    if((d == LONG_MAX || d == LONG_MIN) && errno == ERANGE ){
        printf("%s Out of range\n", c);
    }
    return 0;
}

Edits:

1. Changed int to long for b and d.
2. Setting errno to 0 before calling into c library.
3. Checking for LONG_MIN also for errors.
4. Changed the order for checks (according to comment below)