Visual C++ can't open include file 'iostream' - c++

Question

I am new to C++. I just started! I tried a code on Visual C++ 2010 Express version, but I got the following code error message.
------ Build started: Project: abc, Configuration: Debug Win32 ------
ugo.cpp
c:\users\castle\documents\visual studio 2010\projects\abc\abc\ugo.cpp(3): fatal error C1083: Cannot open include file: 'iostream': No such file or directory
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
This is the code:
// first.cpp -- displays a message
#include <iostream> // A PREPROCESSOR directive
int main(void) // Function header
{ // Start of a function body
using namespace std;
cout << "Come up and C++ me sometime.\n"; // Message
// Start a new line
cout << "Here is the total: 1000.00\n";
cout << "Here we go!\n";
return 0;
}

Answer 1

Replace
#include <iostream.h>
with
using namespace std;
#include <iostream>

Answer 2

Some things that you should check:
Check the include folder in your version of Visual Studio (in "C:\Program Files\Microsoft Visual Studio xx.x\VC\include", check for the file which you are including, iostream, make sure it's there).
Check your projects Include Directories in <Project Name> → Properties → Configuration Properties → VC++ Directories → Include Directories (it should look like this: $(VCInstallDir)include;$(VCInstallDir)atlmfc\include;$(WindowsSdkDir)include;$(FrameworkSDKDir)\include;)
Make sure that you selected the correct project for this code
(menu File → New → Project → Visual C++ → Win32 Console Application)
Make sure that you don't have <iostream.h> anywhere in your code files, Visual Studio doesn't support that (in the same project, check your other code files, .cpp and .h files for <iostream.h> and remove it).
Make sure that you don't have more than one main() function in your project code files (*in the same project, check your other code files, .cpp and .h files for the* main()` function and remove it or replace it with another name).
Some things you could try building with:
Exclude using namespace std; from your main() function and put it after the include directive.
Use std::cout without using namespace std;.

Answer 3

I had this exact same problem in Visual Studio 2015. It looks like as of Visual Studio 2010 and later you need to include #include "stdafx.h" in all your projects.
#include "stdafx.h"
#include <iostream>
using namespace std;
The above worked for me. The below did not:
#include <iostream>
using namespace std;
This also failed:
#include <iostream>
using namespace std;
#include "stdafx.h"

Answer 4

You are more than likely missing $(IncludePath) within Properties → VC++ Directories → Include Directories.
Adding this should make iostream and others visible again. You probably deleted it by mistake while setting up your program.

Answer 5

If your include directories are referenced correctly in the VC++ project property sheet → Configuration Properties → VC++ directories → Include directories, the path is referenced in the macro $(VC_IncludePath).
In my Visual Studio 2015 this evaluates to:
"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\include"
using namespace std;
#include <iostream>
That did it for me.

Answer 6

It is possible that your compiler and the resources installed around it were somehow incomplete. I recommend re-installing your compiler: it should work after that.

Answer 7

I got this error when I created an 'Empty' console application in Visual Studio 2015. I recreated the application, leaving the 'Empty' box unchecked. It added all of the necessary libraries.

Answer 8

Make sure you have Desktop Development with C++ installed.
I was experiencing the same problem, because I only had Universal Windows Platform Development installed.

Answer 9

Microsoft Visual Studio is funny. When you're using the installer, you must checkbox a lot of options to bypass the .NET framework (somewhat) to make more C++ instead of C# applications, such as the CLR options under desktop development... in the Visual Studio installer.... the difference is the C++ Win32 console project or a C++ CLR console project.
So what’s the difference? Well, I'm not going to list all of the files CLR includes, but since most good C++ kernels are in Linux... So CLR allows you to bypass a lot of the Windows .NET framework because Visual Studio was really meant for you to make applications in C#.
Here’s a C++ Win32 console project!
#include "stdafx.h"
#include <iostream>
using namespace std;
int main()
{
cout << "Hello, World!" << endl;
return 0;
}
Now here’s a C++ CLR console project!
#include "stdafx.h"
using namespace System;
int main(array<System::String ^> ^args)
{
Console::WriteLine("Hello, World!");
return 0;
}
Both programs do the same thing .... the CLR just looks more frameworked class overloading methodology, so Microsoft can great its own vast library you should familiarize yourself with if so inclined.
Keywords (C++)
Other things you'll learn from debugging to add for error avoidance:
#ifdef _MRC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif

Answer 10

If you created an environment variable with the name IncludePath, try renaming it to something else.
This name will override $(IncludePath) inside project properties.

Answer 11

Quick fix for small programs:
Add: #include <cstdlib>

Answer 12

In my case, my Visual Studio 2015 installed without selecting C++ package, and Visual Studio 2017 is installed with the C++ package. If I use Visual Studio 2015, opening a C++ project will show this error, and using Visual Studio 2017 will be no error.

Answer 13

I had this problem too. I used this code (before main();) in Visual Studio 2022, and it turned OK:
#include "pch.h"
#include <iostream>
using namespace std;
using namespace winrt;
using namespace Windows::Foundation;

Answer 14

In my case, the error occurred when I created a file in VS Code, without giving the .cpp extension. It resolved when I renamed it with the .cpp.

Answer 15

// first.cpp -- displays a message
#include <iostream> // a PREPROCESSOR directive
using namesapce std;
int main() // function header
{ // start of a function body
///using namespace std;
cout << "Come up and C++ me sometime.\n"; // message
// start a new line
cout << "Here is the total: 1000.00\n";
cout << "Here we go!\n";
return 0;
}