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Function Details : realloc

void *realloc(void * ptr,size_t size) ;

Return Type : void *

New Generic pointer that can point to any data type
Read about return values of realloc function .

1st Parameter Type : void *

New Generic pointer that can point to any data type

1st Parameter

Pointer to the previously allocated memory block. If `ptr` is `NULL`, the function behaves like `malloc`.

2nd Parameter Type : size_t

Platform-specific unsigned type for array indices and memory sizes.

2nd Parameter

The new size in bytes for the memory block. If `size` is 0 and `ptr` is not `NULL`, the memory block is freed.

Read more about parameters of realloc in parameters section
The reallocfunction in C language Changes the size of the memory block pointed to by ptr.
The realloc function changes the size of the memory block pointed to by ptr to size bytes. The contents of the memory block are preserved up to the lesser of the new and old sizes. If the new size is larger, the value of the newly allocated portion is indeterminate. If ptr is NULL, the call is equivalent to malloc(size). If size is zero and ptr is not NULL, the call is equivalent to free(ptr).
The reallocfunction takes 2 parameters:
  • •
    void * `ptr`: Pointer to the previously allocated memory block. If `ptr` is `NULL`, the function behaves like `malloc`.
  • •
    size_t `size`: The new size in bytes for the memory block. If `size` is 0 and `ptr` is not `NULL`, the memory block is freed.
Resizes the memory block pointed to by `ptr` to the new size specified by `size`. The contents of the memory block are preserved up to the lesser of the old and new sizes. Returns a pointer to the resized memory block or `NULL` if the operation fails. The original block is left untouched if reallocation fails.
The realloc function return value :
  • Returns a pointer to the newly allocated memory, or NULL if the request fails
  • The returned pointer may be the same as ptr if the allocation was not moved, or a different pointer if it was moved

Output

This example demonstrates basic usage of realloc(). It allocates memory for 5 integers, initializes them, then reallocates memory for 10 integers, preserving the original data and adding new data.