One of it includes changing the size of an array. An array is collection of items stored at continuous memory locations. As it can be seen that the length size of the array above made is 9. But what if there is a requirement to change this length size. For Example, If there is a situation where only 5 elements are needed to be entered in this array. In this case, the remaining 4 indices are just wasting memory in this array.
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C Tutorial — The functions malloc and free The function malloc is used to allocate a certain amount of memory during the execution of a program. The malloc function will request a block of memory from the heap.
If the request is granted, the operating system will reserve the requested amount of memory. When the amount of memory is not needed anymore, you must return it to the operating system by calling the function free.
The malloc statement will ask for an amount of memory with the size of an integer 32 bits or 4 bytes. If there is not enough memory available, the malloc function will return a NULL. If the request is granted a block of memory is allocated reserved. The address of the reserved block will be placed into the pointer variable. The if statement then checks for the return value of NULL.
If the return value equals NULL, then a message will be printed and the programs stops. The number twenty-five is placed in the allocated memory. Then the value in the allocated memory will be printed. Before the program ends the reserved memory is released. Malloc and structures A structure can also be used in a malloc statement. This notation is not often used. Never use this notation malloc 4. Requesting 4bytes for the integer in the examples.
This will make your code much more portable. If you look at the dynamic memory functions of the stdlib. The following four dynamic memory functions can be found in the stdlib.
Description des mécanismes d'allocation dynamique de mémoire en langage C
Allocation dynamique de la mémoire en c