The include iostream exists but I get an error identifier cout is undefined Why

Question

I learn C   and COM through the books   In the IDE MS Visual Studio 2012 I have created new empty C   project  and added some existing files to it  My CPP file contains  include lt iostream gt  row  but in editor I got such messages      Error  identifier  cout  is undefined   end     Error  identifier  endl  is undefined   Screen     Why it happens

User · Answer

The problem is the std namespace you are missing  cout is in the std namespace   Add using namespace std   after the  include

User · Answer

You need to specify the std   namespace   std  cout  lt  lt        lt  lt  std  endl     Alternatively  you can use a using directive   using std  cout  using std  endl   cout  lt  lt        lt  lt  endl    I should add that you should avoid these using directives in headers  since code including these will also have the symbols brought into the global namespace  Restrict using directives to small scopes  for example   include  lt iostream gt   inline void foo       using std  cout    using std  endl    cout  lt  lt   Hello world   lt  lt  endl      Here  the using directive only applies to the scope of foo

User · Answer

You can add this at the beginning after  include  lt iostream gt    using namespace std

User · Answer

cout is in std namespace  you shall use std  cout in your code  And you shall not add using namespace std  in your header file  it s bad to mix your code with std namespace  especially don t add it in header file

[c++] The #include<iostream> exists, but I get an error: identifier "cout" is undefined. Why?

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