memcpy c++ usage

memcpy is a function in C++ that is used to copy a block of memory from one location to another. It is declared in the <cstring> header file.

Syntax

The syntax for memcpy is as follows:

void memcpy(void destination, const void* source, size_t num);

Parameters

1. destination: Pointer to the destination array where the content is to be copied.
2. source: Pointer to the source of data to be copied.
3. num: Number of bytes to be copied.

Return Value

The memcpy function returns a pointer to the destination array.

Explanation of Steps

1. The memcpy function is called with the destination, source, and number of bytes to be copied as parameters.
2. The function starts by checking if the number of bytes to be copied is zero. If so, it simply returns the destination pointer without performing any copying.
3. Next, the function checks if the destination and source pointers are the same. If they are the same, the function also returns the destination pointer without performing any copying.
4. If the destination and source pointers are different, the function starts copying the bytes from the source to the destination.
5. The function uses an optimized implementation to copy the bytes efficiently. It typically works by copying the bytes in blocks, rather than byte by byte, to improve performance.
6. After copying the bytes, the function returns the destination pointer.

Example Usage

Here is an example usage of memcpy:

#include <iostream>
#include <cstring>

int main() {
    char source[] = "Hello, world!";
    char destination[15];

    memcpy(destination, source, sizeof(source));

    std::cout << "Copied string: " << destination << std::endl;

    return 0;
}

In this example, the memcpy function is used to copy the contents of the source array to the destination array. The size of the source array is passed as the number of bytes to be copied. After the copying is done, the copied string is printed to the console.