title: Why VScode display"'iostream' file not found"in .h file?
body: <pre><code>//vector.h
  #ifndef MYVECTOR_H_
  #define MYVECTOR_H_
  
  #include&lt;iostream&gt;
  #include&lt;vector&gt;
  using namespace std;
  
  class vectors
  {
  public:
      vectors(void);
      ~vectors(void);
      vectors(int *vec,int n);
      vectors(vectors &amp;a);
      friend vectors operator + (vectors a, vectors b);//加法
      friend vectors operator - (vectors a, vectors b);//减法
      friend vectors operator ++(vectors a);//前自增
      friend vectors operator ++(vectors a,int n);//后自增
      friend vectors operator --(vectors a);//前自减
      friend vectors operator --(vectors a,int n);//后自减
      friend vectors operator * (vectors a,vectors b);//数乘
  
      void Display();//显示函数
  
  private:
      int * Vec;//向量指针
      int N;//维数
  };
  
  vectors::vectors(void)
  {
  
  }
  
  }
  #endif
  </code></pre>
  
  <p>I'm writing a header file by C++ in VScode, but VScode show me:</p>
  
  <p>'iostream' file not found</p>
  
  <p>In cpp file, it never happens. I think I should install all it need. And I never meet it before.So I don't know how to do with it.</p>
  
  <p>Ok, I try to give more details.</p>
  
  <p>I use vscode to write code. In last codes, I just used '.cpp' files, so I haven't get an error report. But in this time, I try to write my header file as above, vscode tell me:<strong>iostream' file not found</strong>. I can't correct it. So I ask someone for help.</p>