How do I make sure that strtol() have returned successfully?

Question

according documentation:

On success, the function returns the converted integral number as a long int value. If no valid conversion could be perfor

Answer 1

You can either check the errno or pass a non-NULL value for the second argument and compare its resulting value to str, like:

char * endptr;
long result = strtol(str, &endptr, 10);
if (endptr > str)
{
    // Use result...
}