字符串循环右移n个

编写一个函数，作用是把一个char组成的字符串循环右移n个。比如原来是“abcdefghi”如果n=2，移位后应该是“hiabcdefgh” 

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bool moveToRightNSteps(char * start, unsigned int n)  
{  
    if( (start == NULL)) return false;  
      
    unsigned int length = strlen(start);  
    if(length != 0)  
    {  
        // while n > string length, n%length to avoid repeat operation  
        n = n%length;  
          
        int m = length - n;         // the starting m num should be moved to the end  
        char * tmp = new char[length + n + 1];      // temporary char array to help move string  
        if(tmp == NULL) return false;  
        //strcpy(tmp, start + m);  
        memcpy(tmp, start + m, n * sizeof(char));  
          
        //strcpy(tmp + n, start);  
        memcpy(tmp + n, start, m* sizeof(char));  
        //tmp[length] = '\0';  
        *(tmp + length) = '\0';  
        memcpy(start, tmp, length*sizeof(char));  
 
        delete [] tmp;  
        tmp = NULL;  
    }  
 
    return true;      
}