Accessing Memory Address

Lesson 26
Author : Afrixi
Last Updated : January, 2023

C - Programming Language

This course covers the basics of programming in C.

In C, you can access the memory address of a variable using the ampersand (&) operator. The memory address is also known as a pointer.

Here’s an example:

#include <stdio.h>

int main() {
    int num = 42;
    printf("Value of num: %d\n", num);
    printf("Address of num: %p\n", &num);  // %p format specifier is used to print memory address
    return 0;
}

Output:

Value of num: 42
Address of num: 0x7ffee224177c

In the example, we declare an integer variable num and assign it a value of 42. We then print the value of num and its memory address using the printf() function. The %p format specifier is used to print the memory address.

We can also declare a pointer variable and assign it the memory address of another variable using the asterisk (*) operator. Here’s an example:

#include <stdio.h>

int main() {
    int num = 42;
    int *ptr = &num;
    printf("Value of num: %d\n", num);
    printf("Address of num: %p\n", &num);
    printf("Value of ptr: %p\n", ptr);
    printf("Value at address pointed by ptr: %d\n", *ptr);
    return 0;
}

Output:

Value of num: 42
Address of num: 0x7ffee224177c
Value of ptr: 0x7ffee224177c
Value at address pointed by ptr: 42

In the example, we declare a pointer variable ptr that points to the memory address of num. We then print the value of num, the memory address of num, the value of ptr, and the value at the memory address pointed by ptr. We use the asterisk (*) operator to access the value at the memory address pointed by ptr. This is known as dereferencing the pointer.

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