c语言-逆置字符串

#include "stdio.h"
#include "string.h"
int main()
   {
        char s[]="张伟伟";
        int len=strlen(s);
        printf("%d\n",sizeof(s));
        printf("%s\n",s);
        int start=0;
        int end=len-3;

        char *p =&s[0];
        char *p1=&s[len-3];
        while(start//下面代码 是1-7 2-8 3-9 进行交换
                char tem=*p;
                *p=*p1;
                *p1=tem;
                p++;
                p1++;
                tem=*p;
                *p=*p1;
                *p1=tem;
                p++;
                p1++;
                tem=*p;
                *p=*p1;
                *p1=tem;
                p++;
                p1-=5;
                start+=3;
                end-=3;
        }   
        printf("%s\n",s);


}

以下是字符串逆置

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "time.h"
#include 

void inverse(char *str)//字符串逆置
{
    char *p1 = str;
    char *p2 = str + strlen(str) - 1;
    while (p1 < p2)
    {
        char tmp = *p1;
        *p1 = *p2;
        *p2 = tmp;
        p1++;
        p2--;
    }
}
int main()
{
    char buf[] = "abcdefg";
    inverse(buf);
    printf("buf=%s\n", buf);
}

void inverse(char *str,int num)//字符串逆置指定逆直前几位
{
    char *p1 = str;
    char *p2 = str + num - 1;
    while (p1 < p2)
    {
        char tmp = *p1;
        *p1 = *p2;
        *p2 = tmp;
        p1++;
        p2--;
    }
}