Dynamic Memory Allocation in C Programming – Complete Guide with Examples

Memory management is one of the most important concepts in C programming. Dynamic memory allocation allows programs to request memory at runtime instead of compile time.

In this article, you will learn everything about dynamic memory allocation in C, including malloc, calloc, realloc, and free.

What Is Dynamic Memory Allocation?

Dynamic memory allocation means allocating memory during program execution.

This is useful when the required memory size is not known in advance.

Why Do We Need Dynamic Memory Allocation?

• Efficient memory usage
• Handling large data
• Flexible program design

malloc() Function

malloc() allocates a block of memory and returns a pointer to it.

int *ptr = (int*)malloc(5 * sizeof(int));

The memory allocated by malloc is uninitialized.

calloc() Function

calloc() allocates memory and initializes all bytes to zero.

int *ptr = (int*)calloc(5, sizeof(int));

Difference Between malloc() and calloc()

• malloc does not initialize memory
• calloc initializes memory to zero

realloc() Function

realloc() is used to resize previously allocated memory.

This is useful when you need more or less memory.

free() Function

free() releases dynamically allocated memory.

Not freeing memory causes memory leaks.

Memory Leak Explained

A memory leak happens when allocated memory is not released.

Over time, this can crash applications.

Best Practices for Dynamic Memory Allocation

• Always check if memory allocation succeeded
• Free memory after use
• Set pointer to NULL after free

Common Interview Questions

• What is dynamic memory allocation?
• Difference between malloc and calloc?
• What is a memory leak?

Final Conclusion

Dynamic memory allocation gives flexibility and power to C programs. Understanding memory management is essential for writing efficient and safe code.

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