#include <stdio.h>
 void fun(char*p);
 int main(){
     char *p="ADFFDHJYET";
     fun(p);
     return 0;
 }
 void fun(char*p){
     char b[45];
     int n=0,k=0;
     for(;*(b+n)=*p;){
         n++;
         if(n%3==0){b[n]=' ';
                    k++;
                    printf("%c%d",b[n],k);}
         p++;
         if(*p=='\0') break;
     }
     printf("\nb[3]=%c",b[3]);
 }
运行结果是：
 空格1空格2空格3
 b[3]=F
 为什么会这样？明明把字符修改了的，为什么结果还是F？