What is the difference between "new" and "malloc" in C?

Table of Contents

• Introduction
• Key Differences Between new and malloc in C
  • 1. Language Support
  • 2. Object Initialization
  • 3. Memory Deallocation
  • 4. Type Safety and Casting
  • 5. Error Handling
• Practical Examples
  • Example 1: Allocating Memory for an Integer in C
  • Example 2: Allocating Memory for an Array in C
• Conclusion

Introduction

C programming uses malloc() for dynamic memory allocation. However, beginners often ask about new, which is not part of the C language but of C++. Understanding the role of malloc() in C is essential to manage memory dynamically, while recognizing that new is exclusive to C++ is key for avoiding confusion.

In this guide, we'll focus on the differences between new (used in C++) and malloc() (used in C), explaining how each works and what features each provides in memory allocation.

Key Differences Between new and malloc in C

1. Language Support

• new: The new operator is part of the C++ language, designed specifically for object-oriented memory allocation. It is not available in the C language.

• malloc(): The malloc() function is part of the C Standard Library (<stdlib.h>). It is used to allocate raw memory dynamically but does not initialize objects or call constructors, making it different from new in C++.

  Example:

2. Object Initialization

• new (C++): Allocates memory and calls the constructor for object initialization, making it useful in C++ for object-oriented programming.

• malloc() (C): Only allocates memory but does not initialize it. For primitive data types, you manually initialize the memory, and for complex structures, you use functions to set up the initial state.

  Example:

3. Memory Deallocation

• delete (C++): Used to free memory allocated with new in C++. It also calls the destructor to clean up any resources held by the object.

• free() (C): In C, you use the free() function to deallocate memory that was allocated using malloc(). It does not handle object destructors (since C doesn't have classes or constructors/destructors like C++).

  Example:

4. Type Safety and Casting

• new (C++): Automatically returns a pointer of the correct type, so no casting is required.

• malloc() (C): Returns a void* pointer, which means you need to explicitly cast the pointer to the correct data type in C.

  Example:

5. Error Handling

• new (C++): In C++, new throws an exception (std::bad_alloc) if memory allocation fails.

• malloc() (C): In C, malloc() returns NULL if it fails to allocate memory. It requires manual error checking to avoid dereferencing a NULL pointer.

  Example:

Practical Examples

Example 1: Allocating Memory for an Integer in C

Example 2: Allocating Memory for an Array in C

Conclusion

In C, malloc() is the standard way to allocate dynamic memory, while new is exclusive to C++ and designed for object-oriented programming. malloc() simply allocates raw memory, and you need to handle initialization and memory deallocation with free(). Understanding this distinction helps you manage memory effectively in C and avoid errors when working with dynamic memory allocation.