Question

I have written a function to implement memcpy

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
char *memcpy(char *dest,char *src,int n){

    char *ch=dest;
    while (n--)
        *ch++=*src++;
    return  dest;
}

int main(){

    char *src="georgia";
    int n=strlen(src);
    char *dest=new char[n];
    std::cout<<*memcpy(dest,src,n)<<std::endl;
    return 0;
}

But it only prints a single g. Why?

Answer 1

Because you’re printing a single character.

std::cout<<*memcpy(dest,src,n)<<std::endl;

This dereferences the destination buffer (*memcpy) and therefore returns the first character of the string (which is g). You should be fine using this:

std::cout << memcpy(dest, src, n) << std::endl;

Other than that, it’s still not gonna work: you need to include the terminating NULL character of your string in the copy, but strlen excludes it from the length of the string; so your buffer is missing 1 character. You need to add 1 to n to balance it, and everything should be fine.

int n = strlen(src) + 1;