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In C programming, memory allocation refers to the process of reserving a block of memory for the storage of data during runtime. To allocate memory dynamically in C, we can utilise the standard library functions malloc(), calloc(), and realloc(). In this post, we’ll talk about memory allocation in C programming and how to use these functions.

Static Memory Allocation:

The “static” keyword in C can be used to statically allocate variables. As a result, a memory space is set aside for the variable during compilation. The memory block’s size, though, is fixed and cannot be changed while the programme is running. Because of this, it is inappropriate for storing data structures with a range of sizes.

Dynamic Memory Allocation:

On the other hand, dynamic memory allocation enables us to allocate memory as it is being used and then resize it as necessary. The three common library functions that were mentioned earlier are used to accomplish this.

To allocate a block of memory with a specific size in bytes, use the malloc() method. A pointer to the first byte of the memory block allocated is returned by the function. Integer ptr = (int) malloc(10 * sizeof(int); for instance, creates a block of memory for 10 integers and returns a reference to the first integer.


To allocate a block of memory for an array with a certain number of elements and elements of a defined size, use the calloc() function. A pointer to the first element of the memory block that was allocated is returned by the function. For instance, int ptr = (int) calloc(10, sizeof(int);; returns a pointer to the first integer while allocating a block of memory for an array of 10 integers.


A block of memory that has already been allocated using the malloc() or calloc functions can be reallocated using the realloc() method (). The function requires two arguments: the new block size and a pointer to the previously allocated memory block. For instance, the memory block that was previously allocated to ptr = (int*) realloc(ptr, 20 * sizeof(int)); is reallocated to a size of 20 integers.

It’s vital to remember that once dynamically generated memory is no longer required, it must be released using the free() method. By doing this, memory leaks are avoided and the memory is returned to the system.


In conclusion, memory allocation is a crucial part of C programming that enables effective runtime data storage and manipulation. When used properly, the powerful malloc(), calloc(), and realloc() functions can assist increase code performance and simplify complex algorithms by allowing us to dynamically allocate memory as needed.

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