How do you allocate memory dynamically in C?

Dynamically allocating memory in C is accomplished through the use of specific functions designed for this purpose, such as malloc(), calloc(), and realloc(). These functions allow a programmer to request a block of memory from the heap during runtime, offering flexibility compared to static memory allocation, which occurs at compile time.

• The malloc(size_t size) function allocates a specified number of bytes and returns a pointer to the first byte of this block. It does not initialize the memory, so it may contain garbage values.

• The calloc(size_t num, size_t size) function allocates memory for an array of elements, initializes all bytes to zero, and returns a pointer to the allocated memory.

• The realloc(void *ptr, size_t new_size) function adjusts the size of a previously allocated memory block. This can be useful for resizing arrays or data structures during program execution.

This dynamic memory allocation is critical for creating data structures whose size can change over the course of execution without knowing the required length beforehand. Other options, such as static arrays and pointers exclusively, do not effectively capture the method by which dynamic memory is allocated when it is required.