中兴笔试题--循环右移字符串

写一函数，完成字串循环右移
如"abcdefghi",循环右移2位后成为"hiabcdefg"

void tranStr( char *pStr, int n );

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

using namespace std;
void tranStr(char *pStr,int num){
    char *back=new char[num+1];
    strcpy(back,pStr+strlen(pStr)-num);
    char *front = new char[strlen(pStr)-num];
    strncpy(front,pStr,strlen(pStr)-num);
    strcat(back,front);
    pStr=back;
}
int _tmain(int argc, _TCHAR* argv[])
{
    char *s1="abcdefghijk";
    tranStr(s1,2);
    cout<<s1<<endl;
}