C Tutorial - 16 - Pointer to Pointer

#include <stdio.h>

int main()
{
    int original = 5;

    //Primary Pointer
    int * priPointer = &original;
    int ** secPointer = &priPointer;

    printf("Address with Pointer: %p \n", priPointer); //Address
    printf("Address without Pointer: %p \n", &original); //Address
    printf("Address of Primary Pointer: %p \n", secPointer); //Address of Address

    printf("------------------------------------------------ \n");

    printf("Value using Variable: %d \n", original);
    printf("Value using Primary Pointer: %d \n", *priPointer);
    printf("Value using Secondary Pointer: %d \n", **secPointer);

    return 0;
}

Result:

Address with Pointer: 000000000061FE14
Address without Pointer: 000000000061FE14
Address of Primary Pointer: 000000000061FE08
------------------------------------------------
Value using Variable: 5
Value using Primary Pointer: 5
Value using Secondary Pointer: 5

Process returned 0 (0x0)   execution time : 0.022 s
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This program demonstrates the use of multiple levels of pointers in C programming.

In this program, we have defined an integer variable original with a value of 5. Then, we have created a primary pointer priPointer which points to the address of original using the & operator.

After that, we have created a secondary pointer secPointer which points to the address of priPointer. This means that secPointer contains the address of priPointer.

We can print the addresses of original, priPointer, and secPointer using the %p format specifier in the printf() function.

To access the value of original through the pointers, we use the * operator. We can print the values of original, priPointer, and secPointer using the printf() function and the * operator.

Finally, we can access the value of original using the secondary pointer secPointer by dereferencing it twice with the ** operator.

Multiple levels of pointers are useful when dealing with complex data structures or when you need to pass a pointer to a pointer as an argument to a function. They allow you to modify the value of a pointer by using another pointer that points to it.