隔三秒输出一次系统时间，程序有关问题。

隔三秒输出一次系统时间，程序问题。。。
#include<stdio.h>
#include<time.h>
#include<string.h>

int main()
{
  int i=0;
  char s[]="Thu Jan 01 08:00:03 1970",a[50]={-1},*p;//想要它隔三秒输出一次系统时间Thu Jan 01 08:00:03 1970
  time_t timep,timep1,timep2;
  time(&timep);
  time(&timep1);
  timep2=timep1-timep;
  p=ctime(&timep2);
  for(;*p!='\0';i++)
  {
  a[i]=*p;
  p++;
  }
  printf("time is:%s\n",a);

  while(strcmp(a,s)!=0)
  {
  time(&timep1);
  timep2=timep1-timep;
p=ctime(&timep2);
for(i=0;*p!='\0';i++)
{
a[i]=*p;
p++;
}  
  }
  printf("time2 is:%s\n",ctime(&timep1));
  return 0;
}

为什么strcmp(a,s)!=0老是判断有问题，总是死循环、、、求教高手

[解决办法]

C/C++ code

#include<stdio.h>#include<time.h>#include<string.h>#include<stdlib.h>int main(){    char s[]="Thu Jan 01 08:00:03 1970", a[50] = {-1}, *p;    time_t timep,timep1,timep2;    time(&timep);    time(&timep1);    timep2=timep1-timep;    p=ctime(&timep2);    strcpy(a, s);    printf("time is:%s\n",a);    printf("%d\n", strcmp(a, s));    while(strcmp(a,s)!= 0)    {        time(&timep1);        timep2=timep1-timep;        p=ctime(&timep2);        strcpy(a, s);    }    printf("time2 is:%s\n",ctime(&timep1));    return 0; }