im having trouble running my console app with the following format.I've looked through dozens of websites and stack overflow questions and non of them were useful.please help me figure this out:
#include "stdafx.h"
#include <iostream
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
}
cannot open source file "stdafx.h"
identifier "_TCHAR" is undefine.
it's a console project and it does'nt create those stdafx.h and stdafx.cpp files.
I have found the answer to this problem on my own.
from the beginning the problem was the version of visual studio .
so apart from the unreadable and unclear form of debugging the vs2012 does,the thing is in vs2012 this form of "int _tmain(int argc, _TCHAR* argv[])" is accepted but in vs2019 this is completely prohibited so as "#include "stdafx.h".
So the key is to know what form you should use for c++ programming in different Visual Studio versions.
Replace _TCHAR with char, and _tmain with main.
_TCHAR is not part of the C++ language, it's an obsolete feature of the Windows API that should not be used today.
You can also remove #include "stdafx.h", it's a common convention when using the Microsoft Visual Studio compiler but it's not required. You may also need to turn off the precompiled headers option in your project.
Related
so I just installed vs2015, and I'm having issues starting a project. For my intro school programming class, we are learning with the win32 console. I started up my own project at home so I could work on my projects at home, but I'm having issues starting. Thanks in advance for any help. Link to image
Your issue is annoying yet simple to fix, before I answer it you're using visual studio 2015 which means by default you would have been "given " a header file and your main would have looked like the following.
#include "stdafx.h"
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}
You can modify the main function, as in remove every thing but int main() but I would suggest not doing this.
The answer to your question is, your program will not compile because you are not using #include "stdafx.h"
simply put that in and your projects will work assuming you code them right...
Also after looking at your picture more closely ( next time post your code here)
I see that your only source file showing is named R4.Que? Rename it R4.cpp
Okay. So I've got a simple question. If I ask it in the wrong place, please correct me. What I want to ask is, why Visual Studio gives me this:
#include "stdafx.h"
int main()
{
return 0;
}
everytime I create a new project? (I know I can select Empty Project, and add mine .cpp file by myself, but I'm just curious. It says #include <stdio.h> and #include <tchar.h>. So what is it for? Are you all using it or something?
And P.S - why there is no (int argc, char** argv) in main declaration? (on my coding course in college I've learned that there may be _tmain(int argc, _TCHAR* argv), when creating something in VS)
Okay. So I've got a simple question. If I ask it in the wrong place, please correct me. What I want to ask is, why Visual Studio gives me this:
...
Well, it depends a bit on the project type you've been choosing from the wizard. Looks like the standard template for a console project.
#include "stdafx.h"
is prepended for any type of translation unit by the wizard. It supports the precompiled header optimizaton mechanism.
why there is no (int argc, char** argv) in main declaration?
Because the template provides the minimum for a valid main() entry routine definition.
When creating a new Win32 project, Visual Studio automatically adds a precompiled header "stdafx.h" to your project, even if you unchecked the 'Empty Project' checkbox.
If you want to disable this, go to your project configuration properties -> C/C++ -> Precompiled Headers and select 'Not Using Precompiled Headers'.
Working with precompiled headers see: https://stackoverflow.com/a/4726838.
And P.S. look at -> https://stackoverflow.com/a/4207223
The precompiled header is for speeding up compile times by compiling the contents of your most frequently included headers only once and then reusing the compile results. You can change its name if you want.
The following is my environment:
Eclipse IDE for C/C++ Developers(Juno)
Qt 4.8.3
Qt Eclipse Integration v1.6.1
mingw(20120426)
When I create a Qt console project, I just can't use C library functions, such as exit(int) or atoi(string).
The error message is such like Function 'exit' could not be resolved.
I have included stdlib.h, but still can't work.
I don't know if there is some relation with index.
20121109 Update
Thanks for give me help!
atoi is just a example!
Although I write program in c++, but sometimes I want use C library, so I tag it c++.
The following is what I include
C:/MinGW/include
C:/MinGW/lib/gcc/mingw32/4.6.2/include
C:/MinGW/lib/gcc/mingw32/4.6.2/include/c++
C:/MinGW/lib/gcc/mingw32/4.6.2/include/c++/backward
C:/MinGW/lib/gcc/mingw32/4.6.2/include/c++/mingw32
C:/MinGW/lib/gcc/mingw32/4.6.2/include-fixed
Others are Qt library.
And the following is main.
#include <QtCore>
#include <QCoreApplication>
#include <cstdlib>
using namespace std;
int main(int argc, char *argv[])
{
std::exit(0);
QCoreApplication a(argc, argv);
return a.exec();
}
I try this way but still get error message Function 'exit' could not be resolved.
Thanks a lot!
First of all, use C++ headers style. For stdlib.h :
#include <cstdlib>
Then, I guess you're not bringing namespace information. Either write :
using namespace std;
(even if I don't recommend it) or
using std::exit using std::atoi;
or use fully qualified names :
std::exit(-1);
Finally, why do you need such functions like atoi ?
I had a similar case which I was able to solve by moving #include <cstdlib> to the top of the list of header includes. This means that one of the other header files had a dependency on something in the cstdlib. This is not really good practice but they're all system header files and trying to correct them would make the code less portable between similar development systems.
I use Eclipse C++ Kepler. This is what I did and it worked for me:
right-click in editor's screen>Run As>Local C/C++ Application.
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;
}
Replace
#include <iostream.h>
with
using namespace std;
#include <iostream>
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;.
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"
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.
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.
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.
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.
Make sure you have Desktop Development with C++ installed.
I was experiencing the same problem, because I only had Universal Windows Platform Development installed.
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
If you created an environment variable with the name IncludePath, try renaming it to something else.
This name will override $(IncludePath) inside project properties.
Quick fix for small programs:
Add: #include <cstdlib>
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.
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;
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.
// 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;
}
I am trying to learn c++ but most of the tutorials and books I have read or looked up teaches you this...
(I am assuming like most tutorials, they are teaching in the beginning to code either in win32 console or CLR console. In either case the following does not work.)
#include <iostream>
int main( )
{
std::cout << "Hello World\n";
return (0);
}
The IDE that i have is Visual C++ 2008 Express edition and they accept code like this
#include "stdafx.h"
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}
Or like this
#include "stdafx.h"
using namespace System;
int main(array<System::String ^> ^args)
{
Console::WriteLine(L"Hello World");
return 0;
}
Honestly I do not no the difference in none of these and I am not sure if I should just download a older compiler so that it works. If someone can tell me what the difference in these are and where to go from there. That will help tremendously. Thanks
[Edited]
I am trying to do a simple hello world. But I get the error "system can not find path specified." I have screenshot that shows what the error looks like. It also is saying that my project is out of date when I clearly save the file before I build it. Apparently it can not find the executable file. I went to the debug fold and did not see any .exe file.
[Edited]
Ok, now When I try to build the project I get the following errors
1>------ Rebuild All started: Project: test, Configuration: Debug Win32 ------
1>Deleting intermediate and output files for project 'test', configuration 'Debug|Win32'
1>Compiling...
1>stdafx.cpp
1>Compiling...
1>test.cpp
1>c:\users\numerical25\desktop\test\test\test.cpp(1) : warning C4627: '#include <iostream>': skipped when looking for precompiled header use
1> Add directive to 'stdafx.h' or rebuild precompiled header
1>c:\users\numerical25\desktop\test\test\test.cpp(6) : error C2653: 'std' : is not a class or namespace name
1>c:\users\numerical25\desktop\test\test\test.cpp(6) : error C2065: 'cout' : undeclared identifier
1>Build log was saved at "file://c:\Users\numerical25\Desktop\test\test\Debug\BuildLog.htm"
1>test - 2 error(s), 1 warning(s)
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========
Here is the code I used
#include <iostream>
#include "stdafx.h"
int main( )
{
std::cout << "Hello World\n";
return (0);
}
Note: I tried using it with and without the #include "stdafx.h" When I tried it without the #include "stdafx.h", it said I might be missing it.
Not sure what you're asking. The first two examples you gave are valid C++ programs that should (will) compile with VC++. The third example is a C++/CLI program that must be compiled with the /CLR compiler switch (this is called Managed C++).
EDIT: Adding more specific information (from a comment below):
The first two examples are standard (native) C++ (albeit, the second example has MS-proprietary macros). They compile to native code. The third is C++/CLI (a "managed" extension to C++). It compiles to managed (.NET) code. Only the third snippet interacts with the .NET framework in any way. All three are absolutely buildable and runnable using the appropriate projects in VS 2008 (no command line necessary)!
Based on your latest update, it looks like you have probably modified some project properties and changed some paths. The app is building, but when you try to run it via VS (you should do this with <Ctrl>+F5, by the way), the executable cannot be found (there are several ways you could have messed this up by changing or playing with various settings).
Please note the difference between building and running. Building is the process of compiling and linking your source code. Running is launching the resulting executable. You seem to be confused between these (judging from your complaints about the "...out of date" dialog box). It is normal to get the "...out of date" dialog box if you try to run without rebuilding after you have made a change to the project (even if that change is saved). Just make sure you click "yes." You need to build the project before you can run it.
My recommendation is to completely delete your project and solution. Create a new empty project, as suggested elsewhere in this now-very-heavyweight thread, and don't modify any project settings. If this doesn't work, something is seriously wrong!
ANOTHER EDIT: Just for completion, since this question kept changing:
As others have already pointed out, your ultimate problem with the first snippet is the use of precompiled headers (PCH). PCH are turned on by default in new VS C++ projects. Their purpose is to speed compilation when many implementation files include the same set of headers -- preventing the compiler from having to parse the header files for each compilation unit.
You have three options:
(Recommended) Disable PCH -- Project Properties --> Configuration Properties --> C/C++ --> Precompiled Headers: Set Create/Use Precompiled Header to Not Using Precompiled Headers. (You don't need to do anything with the "stdafx.h" file or the #include for it.)
Place your commonly used #includes in "stdafx.h". In your case, you would put #include <iostream> in "stdafx.h".
Place your #includes after `#include "stdafx.h". Microsoft requires that the "stdafx.h" be the first included file in a compilation unit.
A minor point, which I don't see elsewhere in the answers: When using precompiled headers, such as your stdafx.h, you need to include them first. Change it to:
#include "stdafx.h"
#include <iostream>
and that should fix the errors about it.
Alternatively, it may be easier to simply switch off precompiled headers: Project > Properties > Configuration Properties > C/C++ > Precompiled Headers > Switch first option to "Not using precompiled headers". They can be useful for big projects but will just be awkward and annoying while you're learning, since they have extra rules (like this "must be included first") which aren't requirements of standard C++ .
The "difference" is pedantic. The latter are just Microsoft-specific entry points.
As you are learning C++, I recommend you use a compiler, and preferably an operating system that lets you focus on C++, and not the platform. For this I recommend g++, on an Linux distribution such as Ubuntu.
Try this tutorial, there are many others that are similar that quickly let you overcome being tied to the tools, and focus on C++.
int main();
int main(int argc, char* argv[]);
These are standard C++.
int _tmain(int argc, _TCHAR* argv[]);
int wmain(int argc, wchar_t* argv[]);
These are Windows-specific to handle Unicode arguments. See What is the difference between _tmain() and main() in C++?.
int main(array<System::String^>^ args);
This is not C++. This is C++/CLI.
For best portability, always use the first form.
Also,
int main(int argc, char** argv, char** envp);
This is a usually seen POSIX extension. Windows supports this form of main too. The envp means (pointer to) environment variables.
int main(int argc, char** argv, char** envp, char** apple);
This is for Mac only, obviously.
void main();
And this is wrong (nonstandard, some compilers (e.g. gcc) will reject it).
Visual C++ Express will compile the first example just fine.
However, you need to ensure the proper project settings:
Create an "Empty Project"
"Add a new item..." to the project via the "Project" menu. Select C++ (.cpp) file.
Copy/Paste code into new file
Press F5 to compile and run.
When "Project is out of date" dialog appears, press "Yes" (build the project)
The steps above ensure VC++ Express does not treat your file as a special Win32/Windows console application.
EDIT: added additional step 5 to prevent "Can't find..." dialog.
I managed to get the same dialog by making sure the exe file does not exist, and answering "No" to the build dialog. With a clean, empty project the exe file does not exist yet. It must be built first. If you answer "no" don't build it, VC++ dutifully does not build the exe and later complains about not being able to find it when it tries to run it later.
As STingRaySC pointed out, all three of your examples will compile in VC2008 express; it's just that examples 2 and 3 are what VC2008 Express will load up initially when you create a project (one of the examples is for Managed C++, as STingRaySC mentioned).
You can just delete the code in your second example (the C++ Win32 Console Application project) and paste in the more standard hello world program from your first example. It should compile and run just fine in VC2008 Express - it did for me.
I. Precompiled header
#include "stdafx.h"
is some kind of tricky stuff that comes your way.
If you create a project VC will normally switch on precompiled header.
This means that one header stdafx.h is created which is compiled only once.
This is done to speed up compile time in big environments. If you start C++
it will confuse you.
If you use stdafx.h it has to be the first header in the cpp file.
II. Unicode (Utf16)
int _tmain(int argc, _TCHAR* argv[])
Microsoft uses UTF16 to implement unicode strings.
This means you get two versions of main.
int main(int argc, char* argv[])
int main(int argc, wchar_t* argv[])
This is also confusing if you start.
To simply start you can use whatever editor you want.
Create the file.
Open a Visdual studio 2008 command prompt
cl main.cpp
main.exe
and you will see Hello World using code from books.
Afterwards try to understand some of the settings of VC.
But you should always use an empty project.
Else you have to care about stdafx, UNICODE, ...
_tmain with the _TCHAR argv is the way the C runtime allows you to handle unicode. If _UNICODE is defined, then _tmain will expand to wmain, and the _TCHAR argument will be of type wchar_t. If _UNICODE is not defined, then _tmain will expand to main, which will be the ANSI standard.
Therefore, so long as _UNICODE is not defined, the second snippet you posted is compliant with the standard.
Lots of waxing lyrical and some misinformation for you sift through already, but I suggest following wonsungi's advice. But to clarify his advice:
File->New->Project
Select Project Type "Win32", then Template "Win32 Console Project"
Give the project a name and location
OK
Select "Application Settings"
Check "Empty Project"
In the "Solution Explorer", right click the "Sources" folder, then Add->New Item
Type the name of the file, in the "name" box using a .cpp extension (you can ignore the templates if you wish).
Enter your code in the new file.
Woot!! I figured it out!!! Below is my original code
#include <iostream>
int main( )
{
std::cout << "Hello World\n";
return (0);
}
It was missing the header file #include "stdafx.h" . So I had to include it in there so I added it like this
#include <iostream>
#include "stdafx.h"
int main( )
{
std::cout << "Hello World\n";
return (0);
}
I was still getting an error like what you see in my edited question at the bottom. So What I did is I took #include and added it in my header file and then it worked!!!!!
Even the the books and alot of tutorials show to add #include to the actual cpp, for some reason in express edition I had to add it to header for it to work. I don't know WHY but it's a solution and now it works.
Download and install Dev-C++ on your system. If the code doesn't work on Visual C++, try it out on Dev-C++ (which uses the GCC compiler). You may get the same results or a different error message. Whenever you get an error message you don't understand, do a Internet search for the error message.