如何清除stdin流 [英] how to clear the stdin stream

问题描述

 ＃include< iostream> 
＃include< vector> 
＃include< stdexcept> 
＃include< stdio.h> 
 
 using namespace std; 
 
 void keep_window_open（）
 {
 cin.clear（）; // clear badbit flag 
 cin.sync（）; // clear stdin stream 
 
 cout<< 请输入要退出的字符\\\
; 
 char ch; 
 cin>> ch; 
 cout<< ch<< endl; 
 return; 
} 
 
 int main（）
 try {
 vector< int> v; 
 int x; 
 
 while（cin>> x）
 {
 v.push_back（x）; 
} 
 for（int i = 0; i <= v.size（）; i ++）
 cout<v [< i< =<< v.at（i）<< endl; // out of range 
 
} catch（exception& oor）{
 cerr<< 超出范围错误：< oor.what（）<< endl; 
 keep_window_open（）; 
 return 1; 
} catch（...）{
 cerr<<exception：something gone wrong\\\
; 
 return 2; 
} 
  

上面的代码是练习C ++异常处理函数。

但是，在Ubuntu 11.04下清除stdin流点时程序无法正常运行，但在Windows下的代码块中运行良好。

此外，为什么fflush（stdin）; can not substitudecin.clear（）; cin.sync（）;？

解决方案

请阅读此常见问题条目

http://faq.cprogramming.com/cgi-bin/smartfaq.cgi?answer=1052863818&id=1043284351

为什么fflush（stdin）错误

和此

http://faq.cprogramming.com/cgi -bin / smartfaq.cgi？answer = 1044873249& id = 1043284392

刷新输入缓冲区 $ b

#include<iostream>
#include<vector>
#include<stdexcept>
#include<stdio.h>

using namespace std;

 void keep_window_open()
{   
    cin.clear();        //clear badbit flag
    cin.sync();        //clear stdin stream

    cout << "Please enter a character to exit\n";
    char ch;
    cin >> ch;
    cout <<ch <<endl;
    return;
}

int main()  
try{
    vector<int> v;
    int x;

    while(cin>>x) 
    {
        v.push_back(x);
    }   
    for(int i=0;i<=v.size();i++)
        cout<<"v["<<i<<"]=="<<v.at(i)<<endl;    //out of range

}catch (exception& oor) {
   cerr << "Out of Range error: " << oor.what() << endl;
    keep_window_open();
    return 1;   
}catch(...){         
    cerr<<"exception :something went wrong\n";
    return 2;
}

the code above is to practice the C++ exception handler function.

However, the program couldn't run correctly at clearing stdin stream point under Ubuntu 11.04, but function well under Windows in Codeblocks . What's wrong?

Besides, why "fflush(stdin);" couldn't substitude "cin.clear(); cin.sync();"? And if there are other methods to clear streams?

thanks for your help!

解决方案

Please read this FAQ entry

http://faq.cprogramming.com/cgi-bin/smartfaq.cgi?answer=1052863818&id=1043284351

Why fflush(stdin) is wrong

and this

http://faq.cprogramming.com/cgi-bin/smartfaq.cgi?answer=1044873249&id=1043284392

Flush the input buffer

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