c字符串的拼接与拷贝

#include "stdafx.h"
#include"stdio.h"
#include"stdlib.h"
#include"string.h"
#include
using namespace std;

void str_cpy(char *str1, char *str2);
int strlen(char *str)
{
int count = 0;
while (*str++)
count++;
return count;
}


 char * str_cat( char * str1,  char *str2)
{
char *tmp;
char *const p=tmp = new char[strlen(str1) + strlen(str2) + 1];
str_cpy(tmp, str1);
while (*tmp)
tmp++;

while (*str2)
{
*tmp = *str2;
str2++;
tmp++;
}

*tmp = '\0';
return p;
}


 void str_cpy(char *const str1, char *str2)
 {
char *tmp = str1;

while (*str2)
{
*tmp = *str2;
tmp++;
str2++;
}
*tmp = '\0';
 }