malloc ( ) function

The malloc ( ) functions allocates a block of memory of specified size from the memory heap. The declaration of malloc ( ) is of the form

                        

void *malloc ( size_t size);

Here size is the number of bytes of storage to be allocated. The size_t corresponds to the data types of the size. The malloc ( ) function returns a void pointer to the newly allocated block of memory. Its type is automatically converted to the type of the pointer on the left side of assignment operator. It it fails to allocate piece of memory, it returns a null pointer. Normally this happens where there is not enough memory.

            Suppose x  is a pointer to int type. Then it can be allocated memory to store 10 elements using the following statement.

                                                                        int *x;

where,

In above example, malloc is a function which reserves memory equal to that much as given in parentheses and return the starting address of that memory to a pointer type variable x.

Here 10*sizeof (int) means a total of 20 bytes is allocated and address is stored in x variable.

The (int) written before the malloc function tells that x is pointing to an integer variable and the malloc function is type casted to return the address of integer variable.

The storage space allocated has no name, therefore the contents are accessed only through pointers. We have continuous memory allocations in case of malloc ( ) function and if sufficient amount of space is not allocated then it returns a NULL.

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