{"id":12653,"date":"2023-02-13T09:02:29","date_gmt":"2023-02-13T09:02:29","guid":{"rendered":"https:\/\/www.prepbytes.com\/blog\/?p=12653"},"modified":"2023-03-02T06:34:57","modified_gmt":"2023-03-02T06:34:57","slug":"dynamic-memory-allocation-in-c","status":"publish","type":"post","link":"https:\/\/prepbytes.com\/blog\/dynamic-memory-allocation-in-c\/","title":{"rendered":"Dynamic Memory Allocation in C"},"content":{"rendered":"

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In this article, we will study about that how memory allocation takes place in c dynamically
\nFunction which are used for dynamic allocation like malloc(),calloc(),realloc(), free()<\/strong>, differences
\nbetween Static Memory Allocation and Dynamic Memory Allocation.<\/strong><\/p>\n

Dynamic Memory Allocation in C Langauge<\/h2>\n

In C, dynamic memory allocation refers to the process of allocating memory at runtime. So as result, this allows for the creation of data structures of variable sizes, such as arrays, linked lists, and trees. In simple words, memory can be allocated after the
\nprogram begins execution. Dynamic memory allocation<\/strong> in c is allocated from the heap using some standard library functions like malloc(),calloc(),realloc(), and free()<\/strong> which are present in <stdlib.h>header<\/p>\n

Difference between Static Memory Allocation and Dynamic Memory Allocation<\/h2>\n\n\n\n\n\n\n\n
\u00a0 Dynamic Memory Allocation<\/th>\n\u00a0 \u00a0\u00a0StaticMemory Allocation<\/th>\n<\/tr>\n<\/thead>\n
Memory is reserved at run time and we can allocate and deallocate<\/td>\nMemory is reserved at compile time and we cannot allocate and deallocate<\/td>\n<\/tr>\n
It uses heap space<\/td>\nIt uses stack space<\/td>\n<\/tr>\n
It is more efficient and provides reusability of memory during run time<\/td>\nIt is less efficient and not provide reusability of memory<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

C malloc()<\/h2>\n

In C, malloc is a function which is in <stdlib.h> header file that is used to dynamically allocate memory at runtime. It takes a single argument, which is the number of bytes to allocate, and returns a pointer to the beginning of the allocated memory. The memory allocated by malloc is not initialized, so it contains garbage values. So it is the responsibility to initialize the memory before using it.<\/p>\n

Note:<\/strong> If space is insufficient, allocation fails and returns a NULL pointer.<\/p>\n

Syntax of Malloc():<\/h3>\n
ptr = (castType*) malloc(size)<\/code><\/pre>\n
Example of Malloc()<\/h3>\n
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C calloc()<\/h2>\n
The C library function calloc() is used to allocate memory for an array of elements of a certain data type and initializes all bits to zero. The function takes two arguments: the number of elements in the array and the size of each element. It returns a pointer to the first byte of the allocated memory, or NULL if the request for memory could not be fulfilled.<\/p>\n
Note:<\/strong> If space is insufficient, allocation fails and returns a NULL pointer.<\/p>\n
Syntax of Calloc():<\/h3>\n
ptr = (castType*)calloc(n, size);<\/code><\/pre>\n
here, \u2018size\u2019 is the size of each element, and \u2018n \u2018is the no. of elements.<\/p>\n
Example of Calloc()<\/h3>\n
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C free()<\/h2>\n
The free() function in the C programming language is used to deallocate memory that has already been allocated using the malloc(), calloc(), or realloc() functions. Releasing the memory block indicated to by the address provided to it, it makes more allocations possible. To stop memory leaks in your program, you must utilize free() on dynamically allocated memory.<\/p>\n
Syntax of Free() in C:<\/h3>\n
free(ptr);<\/code><\/pre>\n
Example of free()<\/h3>\n
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C realloc()<\/h2>\n
By the word we understand \u201crealloc\u201d which means re-allocation in C programming, the realloc() function is used to change the size of a previously allocated memory block. It takes two arguments: a pointer to the memory block that you want to resize and the new size of the memory block. If the new size is larger than the original size, the function may move the memory block to a new location in order to accommodate the increased size. If the new size is smaller than the original size, the function will truncate the memory block to the new size. The syntax for the realloc() function is as follows:<\/p>\n
Syntax of realloc()<\/h3>\n
ptr = realloc(ptr, newSize);<\/code><\/pre>\n
where ptr is reallocated with new size ‘newSize’.<\/p>\n
Example of realloc() in C<\/h3>\n
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Note:<\/strong> If space is insufficient, allocation fails and returns a NULL pointer.<\/p>\n
Code Implementation:<\/strong><\/p>\n\t\t\t\t\t\t