回文输出

对一个字符串回文输出，如“how are you doing”，回文后输出应该是“doing you are how”，注意，倒序的只是单词的顺序，但是每个单词内部的字母仍然是按照原来的顺序输出。程序如下：

#include <stdio.h>
void main(void)
{
    char arr[] = "how are you doing";
    char *p, *p1, *pnext, *head;
    char temp;
    head = arr;
    p = arr;
    p1 = arr;
    while (*p1 != '\0')
    {
        p1++;
    }
    p1--;
    while (p1 > p)
    {
        temp = *p1;
        *p1 = *p;
        *p = temp;
        p++;
        p1--;
    }
    p = head;
    p1 = head;
    while (*p != '\0')
    {
        while ((*p1 != ' ')&&(*p1!='\0'))
        {
            p1++;
        }
        if (*p1 == '\0')
        {
            pnext = p1;
        }
        else
        {
            pnext = p1 + 1;
        }
        p1--;
        while (p1 > p)
        {
            temp = *p1;
            *p1 = *p;
            *p = temp;
            p1--;
            p++;
        }
        p = pnext;
        p1 = pnext;
    }
    printf("%s", head);
}