what does strcpy do in c code example

Example 1: strcpy c implementation

#include <stdio.h>
 
// Function to implement strcpy() function
char* strcpy(char* destination, const char* source)
{
    // return if no memory is allocated to the destination
    if (destination == NULL)
        return NULL;
 
    // take a pointer pointing to the beginning of destination string
    char *ptr = destination;
 
    // copy the C-string pointed by source into the array
    // pointed by destination
    while (*source != '\0')
    {
        *destination = *source;
        destination++;
        source++;
    }
 
    // include the terminating null character
    *destination = '\0';
 
    // destination is returned by standard strcpy()
    return ptr;
}
 
// Implement strcpy function in C
int main(void)
{
    char source[] = "Techie Delight";
    char destination[25];
 
    printf("%s\n", strcpy(destination, source));
 
    return 0;
}

Example 2: strcpy implementation in c

while ((*destination++ = *source++) != '\0');