c语言，以单词为单位逆序字符串

#include "string.h"
#include "stdio.h"

char * nixu(char *c)
{
    int  i=0;
    int n = strlen(c);
    char *p1 = c + n -1;
    char *p2 = c;
    char *p3 = c;
    while(p1>p2)
    {
        char a;
        a = *p1;
        *p1 = *p2;
        *p2 = a;
        p1--;
        p2++;
    }
    return p3;
}
char *word(char *c)
{
    char *p = c;
    int n = strlen(c);
    int i = 0,j=0;
    for(i;i<n;i++)
    {
        if(*p == ' ')
        {
            *p = '\0';
            nixu(p-j);
            *p = ' ';
            j=0;
        }
        else
            j++;
        p++;
    }
    p-=n;
    return p;
}

int main()
{
    char a[] = "I love china";
    printf("%s\n",word(nixu(a)));
    return  0;
}