C2065 'cout': undeclared identifier [closed] - c++

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So I'm a complete noob to C++ and I'm trying to make a simple "Hello world" program for an assignment. My code is below:
#include "stdafx.h"
#include <iostream>
using namespace std;
int main() {
cout<<"hello world!";
return 0;
}
For some reason, VS2017 is throwing an error at cout, saying it's undefined. I've done some reading on old posts about this and added in #include "stdafx.h to see if that would solve it as per old advice, but it continues to give me the error. Any ideas?
EDIT:
Again a complete noob but there are multiple version of stdafx.h that come up when I search for it, here's what looks like the "main" one:
// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently,
// but are changed infrequently
#pragma once
#ifndef STRICT
#define STRICT
#endif
#include "targetver.h"
[!if SERVICE_APP]
#define _ATL_FREE_THREADED
[!else]
#define _ATL_APARTMENT_THREADED
[!endif]
#define _ATL_NO_AUTOMATIC_NAMESPACE
#define _ATL_CSTRING_EXPLICIT_CONSTRUCTORS // some CString constructors will be explicit
[!if PREVIEW_HANDLER || THUMBNAIL_HANDLER || SEARCH_HANDLER]
#ifdef _MANAGED
#error File type handlers cannot be built as managed assemblies. Set the Common Language Runtime options to no CLR support in project properties.
#endif
#ifndef _UNICODE
#error File type handlers must be built Unicode. Set the Character Set option to Unicode in project properties.
#endif
#define SHARED_HANDLERS
[!endif]
[!if SUPPORT_MFC]
#include <afxwin.h>
#include <afxext.h>
#include <afxole.h>
#include <afxodlgs.h>
#include <afxrich.h>
#include <afxhtml.h>
#include <afxcview.h>
#include <afxwinappex.h>
#include <afxframewndex.h>
#include <afxmdiframewndex.h>
#ifndef _AFX_NO_OLE_SUPPORT
#include <afxdisp.h> // MFC Automation classes
#endif // _AFX_NO_OLE_SUPPORT
[!endif]
[!if SUPPORT_COMPLUS]
#include <comsvcs.h>
[!endif]
#define ATL_NO_ASSERT_ON_DESTROY_NONEXISTENT_WINDOW
#include "resource.h"
#include <atlbase.h>
#include <atlcom.h>
#include <atlctl.h>

Answer 1

error C2065: 'cout': undeclared identifier is a result of the absence of #include <iostream>. The first cause might be stdafx.h content. The one you provided, I'm not so sure how it is related to your main.cpp/project. Let's start from a fresh project: ...VS2017 IDE: Create new project, ConsoleApplication project-type, & replace the main() function with yours.
A VS2017 IDE (15.8.2) fresh ConsoleApplication project: ConsoleApplication1
// ConsoleApplication1.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
using namespace std;
int main() {
cout << "hello world!";
return 0;
}
stdafx.h: (Generated by the IDE)
// stdafx.h : include file for standard system include files,
// or project specific include files that are used frequently, but
// are changed infrequently
//
#pragma once
#include "targetver.h"
// TODO: reference additional headers your program requires here
stdafx.cpp: (Generated by the IDE)
// stdafx.cpp : source file that includes just the standard includes
// ConsoleApplication1.pch will be the pre-compiled header
// stdafx.obj will contain the pre-compiled type information
#include "stdafx.h"
// TODO: reference any additional headers you need in STDAFX.H
// and not in this file
targetver.h: (Generated by the IDE)
#pragma once
// Including SDKDDKVer.h defines the highest available Windows platform.
// If you wish to build your application for a previous Windows platform, include WinSDKVer.h and
// set the _WIN32_WINNT macro to the platform you wish to support before including SDKDDKVer.h.
#include <SDKDDKVer.h>
** This code runs perfectly. **
--
"there are multiple versions of stdafx.h that come up when I search for it" - What do you mean? In your project? On the internet? You can't just take one stdafx.h from the internet. stdafx.h content is tailored per project, not universal. What I provided above, for example, is the IDE default new ConsoleApplication project stdafx.h. You may add to the file according to your project needs.