Memory Allocation in C++

Memory allocation is a fundamental concept in programming, and in C++, it plays a crucial role in managing the memory required by your programs. Proper memory allocation and management are essential to ensure your programs run efficiently and without memory leaks or crashes.
Memory allocation is the process of setting aside a block of memory for a program to use during runtime.In C++, memory allocation can be categorized into two main types: static and dynamic memory allocation.

In the below PDF we discuss about Memory Allocation in C++  in detail in simple language, Hope this will help in better understanding.

1. Static Memory Allocation:

Static memory allocation occurs at compile time, and the memory is allocated at the program’s start and deallocated at its end. In this scenario, the compiler determines the size of the memory required for variables and allocates memory accordingly.

int main() {
int x; // Static allocation of 'x'
// ...
return 0;

Static memory allocation is straightforward but limited in flexibility. The size of memory cannot change during runtime, making it unsuitable for situations where you need to allocate memory dynamically.

2. Dynamic Memory Allocation:

Dynamic memory allocation, on the other hand, occurs at runtime and allows for more flexibility. It allows you to allocate memory on demand and release it when it’s no longer needed. In C++, you typically use the new operator to allocate memory dynamically and the delete operator to deallocate it.

int main() {
int* p = new int; // Dynamic allocation of an integer
// ...
delete p; // Deallocate the memory
return 0;

Dynamic memory allocation is particularly useful when dealing with data structures like linked lists, trees, or when the memory requirements are not known in advance.

Common Dynamic Memory Allocation Functions:

1. new and delete Operators:
As mentioned earlier, the new operator allocates memory on the heap, and the delete operator deallocates it. When using new, don’t forget to use delete to free the memory to avoid memory leaks.

int* p = new int; // Allocate memory
delete p; // Deallocate memory

2. malloc and free Functions:
C++ also supports C-style memory allocation functions malloc and free. These functions allocate and deallocate memory on the heap. However, they require manual memory management and don’t call constructors and destructors for user-defined types.

int* p = (int*)malloc(sizeof(int)); // Allocate memory

Related Question

Memory allocation in C++ refers to the process of reserving a portion of a computer’s memory for storing data during a program’s execution.


The ‘new’ operator in C++ is used for dynamic memory allocation. It allocates memory on the heap and returns a pointer to the allocated memory.

Memory allocated with the ‘new’ operator should be deallocated using the ‘delete’ operator. Failing to do so can result in memory leaks.

The ‘malloc()’ function is used for dynamic memory allocation in C++. It allocates a specified number of bytes on the heap and returns a void pointer to the allocated memory.

Memory allocated with ‘malloc()’ should be deallocated using the ‘free()’ function. Failure to free allocated memory can lead to memory leaks.


Storage Classes in C++ In

Preprocessors in C++ A preprocessor

Standard Template Library in C++

Exception Handling in C++ Exception

Destructors in C++ A destructor

Constructors in C++ A constructor

Inheritance in C++ Inheritance is

7 thoughts on “Memory Allocation in C++”

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