What is realloc?
`realloc` is a C programming language function used to resize dynamically allocated memory blocks. It takes a pointer to a previously allocated memory block and adjusts its size. If the new size is larger, it may extend or move the block, preserving its content. If the new size is smaller, it may truncate the block. The function returns a pointer to the resized memory block or `NULL` if the operation fails. Proper use of `realloc` helps optimize memory usage and avoid memory leaks or segmentation faults in dynamic memory management.