C语言：实现一个函数，可以左旋字符串中的k个字符。

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include <string.h>
void reserve(char *left,char*right)
{
 while (left < right)
 {
  char tmp = *left;
     *left = *right;
  *right = tmp;
  left++;
  right--;
 }
}
int main()
{
 char arr[10] = "AABCD"; 
 int len = strlen(arr)-1;
 int k = 0;
 char *pstart = &arr[0];
 char *pend = arr+len;
 scanf("%d", &k);
 reserve(pstart, pstart + k -1);
 reserve(pstart + k, pend);
 reserve(pstart, pend);
 printf("%s\n", arr);
 system("pause");
 return 0;
}