C++ free vs delete

In C++, the free and delete operations are used for memory deallocation, but they have different usage and behavior. This article will discuss the differences between free and delete and provide a comprehensive overview for programmers.

free operator

The free operator is used to deallocate memory that was previously allocated using the malloc, calloc, or realloc functions. Here are some key points about free:

• Syntax: free(pointer);
• pointer must be a pointer to the memory block previously allocated dynamically.
• It does not call the destructor of the object.
• It is a function from C standard library <cstdlib>, imported in C++ through <stdlib.h> or <cstdlib>.
• It operates on void pointers, so casting is required.
• It cannot be used with arrays allocated using new[].
• If pointer is a null pointer, no operation is performed.

Markdown code for free:

// Example of using free
free(pointer);

delete operator

The delete operator is used to deallocate memory that was previously allocated using the new operator. Here are some key points about delete:

• Syntax: delete pointer; or delete[] pointer; (for arrays)
• pointer must be a pointer to an object or an array of objects previously created dynamically.
• It calls the destructor of the object(s) before deallocating the memory.
• It is an operator in C++, no need to include any additional libraries.
• It automatically determines the size of the allocated block based on the type.
• It can be used with arrays created using new[].
• If pointer is a null pointer, no operation is performed.

Markdown code for delete:

// Example of using delete
delete pointer;

// Example of using delete with arrays
delete[] arrayPointer;

Considerations and Best Practices

• It is important to pair the appropriate deallocation method based on the allocation method used (free with malloc, calloc, or realloc; delete with new or new[]).
• Mixing free and delete is undefined behavior and should be avoided.
• Avoid memory leaks by always deallocating dynamically allocated memory when it is no longer needed.
• Use smart pointers like std::unique_ptr or std::shared_ptr to handle memory management automatically, reducing the need for explicit deallocation.

Remember to use the appropriate deallocation method (free or delete) based on how the memory was allocated. Be cautious with memory management to avoid issues like memory leaks or accessing deallocated memory. Utilize modern C++ features like smart pointers whenever possible to automate memory management and improve program robustness.