程序代码：

#include<stdio.h>
#include<string.h>
int fun(char *w,int n){
    char t,*s1=w,*s2=w+n-1;
    while(s1<s2){
        t=*s1++;
        *s1=*s2--;
        *s2=t;
    }
}
main(){
    char p[]="1234567";
    fun(p,strlen(p));
    puts(p); 
}