An In-Depth Understanding of Memory and Pointers in C/

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Comparing Pointers

Comparing Pointers

Learn to compare pointers.

We'll cover the following...

Introduction

Pointers hold memory addresses, which are just numbers. Every comparison operator that works on numbers also works on pointers—<,>,<=,>=,==, and !=.

We won’t present an example for all of them as it will get pretty repetitive.

Fixing the code

We will try to use the comparison operator and improve the code we used in the Addition and Subtraction lesson.

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#include <stdio.h>



int main()

{

    int a = 5, b = 6;



    printf("&a = %u | &b = %u\n", &a, &b);



    int *ptr = &b;

    printf("[Before ++]Reading thru the pointer: %d\n", *ptr); //will read the value of b

    ptr++;

    printf("[After ++]Reading thru the pointer: %d\n", *ptr); //will read the value of a



    return 0;

}

Using the code that we previously used for incrementing and decrementing, we’ll explore the comparison operators. We had two variables on the stack. Then, we created a pointer for one of them and then incremented or decremented it to get to the other variable.

What we did falls into the undefined behavior category. That is, the code isn’t portable and not guaranteed to work. On another system, the compiler may decide to switch ...