error C2065 cout undeclared identifier

Question

I am working on the  driver  part of my programing assignment and i keep getting this absurd error      error C2065   cout    undeclared identifier   I have even tried using the std  cout but i get another error that says  IntelliSense  namespace  std  has no member  cout  when i have declared using namespace std  included iostream   i even tried to use ostream  I know it s a standard noob question but this has stumped me and I m a novice  meaning  I ve programed before       include  lt iostream gt  using namespace std   int main          cout  lt  lt   hey   lt  lt  endl   return 0      I m using Visual Studio 2010 and running Windows 7  All of the  h files have  using namespace std  and include iostream and ostream

User · Answer

I ran across this error after just having installed vs 2010 and just trying to get a nearly identical program to work.

I've done vanilla C coding on unix-style boxes before, decided I'd play with this a bit myself.

The first program I tried was:

#include "stdafx.h"


int _tmain(int argc, _TCHAR* argv[])
{
    cout << "Hello World!";
    return 0;
}

The big thing to notice here... if you've EVER done any C coding,

int _tmain(int argc, _TCHAR* argv[])

Looks weird. it should be:

int main( int argc, char ** argv )

In my case I just changed the program to:

#include <iostream>
using namespace std;

int main()
{
     cout << "Hello world from  VS 2010!\n";
     return 0;
}

And it worked fine.

Note: Use CTRL + F5 so that the console window sticks around so you can see the results.

User · Answer

write this code  it works perfectly     include  stdafx h   include  lt iostream gt   using namespace std   int main      cout lt  lt  Hello World      return 0

User · Answer

If you started a project requiring the  include  stdafx h  line  put it first

User · Answer

In VS2017  stdafx h seems to be replaced by pch h see this article   so use    include  pch h   include  lt iostream gt   using namespace std   int main         cout  lt  lt   Enter 2 numbers    lt  lt  endl

User · Answer

Just use printf   Include stdio h in your stdafx h header file for printf

User · Answer

I had same problem on Visual Studio C   2010   It s easy to fix   Above the main   function just replace the standard include lines with this below but with the pound symbol in front of the includes     include  stdafx h    include  lt iostream gt  using  namespace std

User · Answer

I had the same issue when starting a ms c   2010 project from scratch - I removed all of the header files generated by ms and but used    include  stdafx h   include  lt iostream gt  using namespace std   int main        cout  lt  lt   hey   lt  lt  endl     return 0      I had to include stdafx h as it caused an error not having it in

User · Answer

In Visual studio use all your header filer below  stdafx h

User · Answer

is normally stored in the C  Program Files Microsoft Visual Studio 8 VC include folder   First check if it is still there   Then choose Tools   Options  Projects and Solutions  VC   Directories  choose  Include files  in the  Show Directories for   combobox and double-check that   VCInstallDir include is on top of the list

User · Answer

If the only file you include is iostream and it still says undefined  then maybe iostream doesn t contain what it s supposed to   Is it possible that you have an empty file coincidentally named  iostream  in your project

User · Answer

When you created your project  you did not set  use precompiled headers  correctly   Change it in properties- C C  - precompiled headers

User · Answer

before you begin this program get rid of all the code and do a simple hello world inside of main   Only include iostream and using namespace std   Little by little add to it to find your issue   cout  lt  lt   hi   lt  lt  endl

User · Answer

Try it  it will work  I checked it in Windows XP  Visual Studio 2010 Express    include  stdafx h   include  lt iostream gt  using namespace std   void main          int i   0     cout  lt  lt   Enter a number        cin  gt  gt  i

User · Answer

The code below compiles and runs properly for me using gcc   Try copy pasting this and see if it works     include  lt iostream gt  using namespace std   int bob  int a    cout  lt  lt   hey   lt  lt  endl  return 0      int main          int a   1      bob a       return 0

User · Answer

Include the std library by inserting the following line at the top of your code   using namespace std

User · Answer

I ve seen similar things happen when I was using the  c file extension with C   code  Other than that  I d have to agree with everyone about a buggy installation  Does it work if you try to compile the project with an earlier release of VS  Try VC   Express 2008  Its free on msdn

User · Answer

The include  stdafx h  is ok  But you can t use cout unless you have included using namespace std   If you have not included namespace std you have to write std  cout instead of simple cout

User · Answer

Take the code    include  lt iostream gt  using namespace std    out of your  cpp file  create a header file and put this in the  h file  Then add   include  whatever your header file is named h    at the top of your  cpp code  Then run it again

User · Answer

Are you sure it s compiling as C     Check your file name  it should end in  cpp    Check your project settings   There s simply nothing wrong with your program  and cout is in namespace std   Your installation of VS 2010 Beta 2 is defective  and I don t think it s just your installation   I don t think VS 2010 is ready for C   yet   The standard  Hello  World  program didn t work on Beta 1   I just tried creating a test Win32 console application  and the generated test cpp file didn t have a main   function   I ve got a really  really bad feeling about VS 2010

User · Answer

I have VS2010  Beta 1 and Beta 2  one on my work machine and one at home   and I ve used std plenty without issues  Try typing   std     And see if Intellisense gives you anything  If it gives you the usual stuff  abort  abs  acos  etc    except for cout  well then  that is quite a puzzler  Definitely look into your C   headers in that case   Beyond that  I would just add to make sure you re running a regular  empty project  not CLR  where Intellisense is crippled   and that you ve actually attempted to build the project at least once  As I mentioned in a comment  VS2010 parses files once you ve added an include  it could be that something stuck the parser and it didn t  find  cout right away   In which case  try restarting VS maybe

User · Answer

I have seen that if you use   include  lt iostream h gt    then you will get the problem   If you use    include  lt iostream gt       notice - without the  h   then you will not get the problem you mentioned

User · Answer

In Visual Studio you must  include  stdafx h  and be the first include of the cpp file  For instance   These will not work    include  lt iostream gt  using namespace std  int main          cout  lt  lt   hey   lt  lt  endl      return 0         include  lt iostream gt   include  stdafx h  using namespace std  int main          cout  lt  lt   hey   lt  lt  endl      return 0      This will do    include  stdafx h   include  lt iostream gt  using namespace std  int main          cout  lt  lt   hey   lt  lt  endl      return 0      Here is a great answer on what the stdafx h header does

User · Answer

I came here because I had the same problem  but when I did  include  stdafx h  it said it did not find that file   What did the trick for me was   include  lt algorithm gt    I use Microsoft Visual Studio 2008    These are the things that you can use then  incl   count   Link

User · Answer

Such a silly solution in my case      Example a  include  lt iostream gt       include  stdafx h    The above was odered as per example a  when I changed it to resemble example b below        Example b  include  stdafx h   include  lt iostream gt      My code compiled like a charm  Try it  guaranteed to work

User · Answer

It was the compiler - I m now using Eclipse Galileo and the program works like a wonder

[c++] error C2065: 'cout' : undeclared identifier

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