编写了一个简单的时钟小程序，是一个死循环，没有办法退出，如果想实现输入特定的字符退出时钟，应该如何修改？
#include<iostream>
#include<time.h>
#include<windows.h>
using namespace std;
int main()
{
void printlocal();
while(1)
{printlocal();
Sleep(1000);
}
return 0;
}
void printlocal() //显示系统时间
{
time_t curtime = time(NULL); //提取系统时间
int nian,yue,ri,shi,fen,miao;
tm bendi; tm* a; //定义beidi类和指针a
a=localtime(&curtime);
bendi=*localtime(&curtime);
nian = bendi.tm_year+1900; //年份从1900开始计算
yue = bendi.tm_mon+1; //月份从0开始
ri = bendi.tm_mday;
shi = bendi.tm_hour;
fen = bendi.tm_min;
miao = bendi.tm_sec;
system("cls");
cout<<"__________________________"<<endl
<<"| - Local Time - |"<<endl
<<"| |"<<endl
<<"| <TIME> "<< shi/10 << shi%10
<< ":"
<< fen/10 << fen%10
<< ":"
<< miao/10 << miao%10
<<" |"<<endl
<<"| <DATE> "<<nian << "/" << yue << "/" << ri <<" |"<<endl
<<"|________________________|"<<endl;
}