constant pointer c++

Constant Pointers in C++

A constant pointer in C++ is a pointer that points to a constant value. It is declared using the const keyword, which specifies that the value being pointed to cannot be modified through the pointer. The syntax for declaring a constant pointer is as follows:

const int* ptr;

In this example, ptr is a constant pointer to an integer. The const keyword is placed before the type being pointed to, indicating that the value cannot be modified through ptr. However, the pointer itself can be reassigned to point to a different memory location.

Explanation of Each Step

1. Declare a constant pointer: Start by declaring a pointer variable using the const keyword. This indicates that the value being pointed to cannot be modified through the pointer.

const int* ptr;

1. Assign a memory address: Next, assign a memory address to the constant pointer using the address-of operator & or by assigning it the value of another pointer.

int num = 10;
ptr = #

1. Access the value: To access the value being pointed to, use the dereference operator *.

int value = *ptr;

1. Modify the pointer: Although the value being pointed to is constant, the pointer itself can be modified to point to a different memory location.

int num2 = 20;
ptr = &num2;

1. Error when modifying the value: Attempting to modify the value being pointed to through a constant pointer will result in a compilation error.

ptr = 30; // Error: assignment of read-only location '(const int*)ptr'

By declaring a constant pointer, you ensure that the value being pointed to cannot be modified through that pointer, providing a level of safety and immutability in your code.