dynamic memory in c++

Dynamic memory in C++ allows you to allocate and deallocate memory at runtime. This is useful when you need to create variables whose size is not known at compile time or when you want to manage memory manually.

To use dynamic memory in C++, you need to perform the following steps:

  1. Allocation: To allocate memory dynamically, you can use the new keyword followed by the type of the object you want to create. For example, to allocate memory for an integer, you can use new int. This will return a pointer to the allocated memory.

  2. Initialization: After allocating memory, you can initialize the object by assigning a value to it. You can use the dereference operator to access the memory pointed to by the pointer. For example, if you have allocated memory for an integer, you can initialize it like this: ptr = 10;, where ptr is a pointer to the allocated memory.

  3. Deallocation: When you are done using the dynamically allocated memory, you need to free it to prevent memory leaks. To deallocate the memory, you can use the delete keyword followed by the pointer to the allocated memory. For example, to deallocate memory for the integer we allocated earlier, you can use delete ptr;, where ptr is the pointer to the allocated memory.

It's important to note that for every new there should be a corresponding delete to free the memory. Failing to deallocate memory can lead to memory leaks, where memory is allocated but never released, causing the program to consume more and more memory over time.

Additionally, C++ provides the new[] and delete[] operators to allocate and deallocate arrays dynamically. These operators work similar to new and delete, but they are used for dynamic arrays.

Here is an example that demonstrates these steps:

int* ptr = new int;  // Step 1: Allocate memory for an integer
*ptr = 10;          // Step 2: Initialize the integer
delete ptr;         // Step 3: Deallocate the memory

This example allocates memory for an integer, initializes it with the value 10, and then frees the memory using delete.