C语言--左旋字符串中的K个字符

问题：

     3.实现一个函数，可以左旋字符串中的k个字符。

        AABCD左旋一个字符得到ABCDA

        AABCD左旋两个字符得到BCDAA

 

#include<stdio.h>
#include<assert.h>
#include<string.h>
void reserve(char* str, int len)
{
    assert(str);
    char* start = str;
    char* end = str + len - 1;
    while (start < end)
    {
        char tmp = *start;
        *start = *end;
        *end = tmp;
        start++;
        end--;
    }
}
void reserve1(char* str, int len, int k)
{
    reserve(str, len);//dcbaa
    assert(str);
    char* start = str ;
     
    if (k < len)
    {
        char* end = str + len - 1 - k;
        while (start < end)
        {
            char tmp = *start;
            *start = *end;
            *end = tmp;
            start++;
            end--;
        }
    }
    else
    {
        printf("输入的字符串个数太大\n");
    }
}
void reserve2(char* str, int len,int s)
{
    assert(str);
    reserve1(str, len, s);//cdbaa
    char* start = str+len-s;
    char* end = str + len - 1;
    while (start < end)
    {
        char tmp = *start;
        *start = *end;
        *end = tmp;
        start++;
        end--;
    }
}
int main(void)
{
    char str[] = "aabcd";
    int len = strlen(str);
    int s;
    printf("请输入要旋转的字符串个数\n");
    scanf_s("%d", &s);
    reserve2(str, len, s);
    printf("%s", str);
}