C++ Programs Dynamic Memory Allocation

Dynamic memory allocation in C++ refers to the process of allocating memory for a variable during runtime. It allows the programmer to control the size of the memory allocation and manage memory more efficiently.

Syntax

data_type *pointer_variable = new data_type;

The new operator dynamically allocates memory for the variable and returns a pointer to the allocated memory. The data_type specifies the type of data the variable represents, and the pointer_variable is a pointer variable that will store the memory address of the allocated memory.

int *num = new int;  // allocate memory for an integer

Example

#include <iostream>
using namespace std;

int main() {
    int *num = new int;  // allocate memory for an integer
    *num = 42;  // assign a value to the integer
    cout << *num << endl;  // print the value of the integer
    delete num;  // free the memory
    return 0;
}

Output

42

Explanation

In the above example, we have dynamically allocated memory for an integer using the new operator and assigned a value to it using the dereference operator (*). We then printed the value and freed the memory using the delete operator.

Use

Dynamic memory allocation is useful when working with complex data structures that have varying sizes and need to be created or destroyed during runtime. It allows for more efficient memory management and can improve program performance.

int size;
cout << "Enter array size: ";
cin >> size;

int *arr = new int[size];  // dynamically allocate memory for an array

// code to populate and manipulate the array

delete[] arr;  // free the memory allocated for the array

In the above example, we dynamically allocate memory for an array of integers based on user input. We then manipulate the array as needed and free the memory once we are done with it.

Important Points

• Dynamic memory allocation allows for more efficient memory management during runtime.
• The new operator is used to allocate memory and returns a pointer to the allocated memory.
• The delete operator is used to free memory allocated using the new operator.
• Dynamic memory allocation is useful for creating and destroying complex data structures.

Summary

In summary, dynamic memory allocation in C++ allows programmers to allocate memory during runtime and manage memory more efficiently. It is useful for working with complex data structures and improving program performance. However, it is important to free memory allocated using the new operator using the delete operator to avoid memory leaks.