#include "stdafx.h"
#include <iostream>
#include <string.h>

using namespace std;

// "JohnDoe"       "Doe"

void myStrCat(char *dest, const char *source)
{
	// skip the dest until you reach its '\0'
	while (*dest != NULL)
		dest++;

	// at this point *dest == '\0'
	while (*source != '\0') {
		*dest = *source;
		++dest;
		++source;
	}

	// at this point *source  == 0
	// at this point *dest == potentially junk
	*dest = 0; // to zero-terminate the string dest.
}

int main()
{
	char fullName[80] = "John";
	char lastName[80] = "Doe";
	myStrCat(fullName, lastName);

	return 0;
}