Question

I am trying to determine the purpose of checking for a pointer being greater than 0:

void someFunction(int *src) {
   int val = *src++;
   if( val > 0 ) {
       // Do something?
   }
}

If the data type is pointer, wouldn’t the value of the pointer always be a memory address? Does doing pointer arithmetic do something that may set val = 0 ?

Is this a simple null pointer check?

Answer 1

That’s not checking if a pointer is greater than zero; it’s checking if the pointed-to value is greater than zero, and simultaneously advancing the pointer by one. Here’s some equivalent code that might help you understand:

void someFunction(int *src) {
   int val = *src; // Dereferencing the pointer
   src++;          // Moving the pointer

   if( val > 0 ) {
       // Do something?
   }
}

val is just an int, not a pointer.