Pointers are one of the most important concepts in C++ programming language. They are used to store the memory address of a variable. Pointers allow us to manipulate the memory directly, which is very useful in many programming scenarios.
In C++, a pointer is a variable that stores the memory address of another variable. The pointer variable itself is stored in memory, and it has its own memory address. Pointers are declared using the asterisk (*) symbol.
Here is an example of how to declare a pointer:
int* ptr;
This declares a pointer variable called "ptr" that can store the memory address of an integer variable. To assign a value to the pointer, we use the address-of operator (&) to get the memory address of the variable we want to point to:
int num = 10;
int* ptr = #
Now, the pointer "ptr" points to the memory address of the variable "num". We can access the value of "num" through the pointer by using the dereference operator (*):
int num = 10;
int* ptr = #
*ptr = 20;
This code sets the value of "num" to 20 by dereferencing the pointer "ptr".
Pointers can also be used to dynamically allocate memory. This means that we can allocate memory at runtime, rather than at compile time. To allocate memory dynamically, we use the "new" operator:
int* ptr = new int;
*ptr = 10;
This code allocates memory for an integer variable and assigns the value 10 to it. The pointer "ptr" now points to this memory location.
When we are done using dynamically allocated memory, we must free it using the "delete" operator:
int* ptr = new int;
*ptr = 10;
delete ptr;
This code frees the memory that was allocated for the integer variable.
Pointers can also be used to create arrays:
int* arr = new int[10];
for (int i = 0; i < 10; i++) {
arr[i] = i;
}
delete[] arr;
This code creates an array of 10 integers using a pointer. We can access the elements of the array using the subscript operator ([]).
Overall, pointers are a powerful tool in C++ programming. They allow us to manipulate memory directly, which can be very useful in many programming scenarios.