title: What's the difference between cin>>x;cin>>y and cin>>x>>y
body: <p>I write a small single program. Here is the code:</p>
  
  <pre><code>#include&lt;iostream&gt;
  using namespace std;
  int main()
  {
    int x;
    float y;
    cout&lt;&lt;"Please input an int number:"&lt;&lt;endl;
    cin&gt;&gt;x;
    cout&lt;&lt;"The input number is x= "&lt;&lt;endl;
    cout&lt;&lt;"Please input a float number:"&lt;&lt;endl;
    cin&gt;&gt;y;
    cout&lt;&lt;"The float number is y= "&lt;&lt;endl;
    return 0;
  }
  </code></pre>
  
  <p>But when I first input the number 69.8, the output is </p>
  
  <pre><code>Please input an int number:
  69.8
  The int number is x= 69
  The float number is y= 0.8
  </code></pre>
  
  <p>I thought it will transfer 69.8 into 69,and then ask me input the next number y, but it input automatically,why?</p>