Run C Code In Visual Studio

First written on 2020-09-11.
Last updated on 2021-01-02.

In this article and several more, I will be discussing developing a very simple C++ library and application using CMake and Visual Studio Code. I will also use git and Google Test, and port the project from Windows to Linux. Most of the information is applicable to using almost any IDE, or indeed, no IDE at all.

Why Use CMake?

How to run and compile C# inside of Visual Studio Code with.NET Core. In this short and simple tutorial I will write about this topic. For this tutorial you will need couple of minutes, VS Code,.NET Core and that's it. So let's begin with tutorial. First of all you will need to have installed Visual Studio Code on your machine. Open code file or select code snippet in Text Editor, then use shortcut Ctrl+Alt+N, or press F1 and then select/type Run Code, or right click the Text Editor and then click Run Code in editor context menu, or click Run Code button in editor title menu, the code will run and the output will be shown in the Output Window. The Visual Studio Code Editor must be installed in the system. Download the C/C Extension. It is an extension provided by Microsoft that support visual studio code. It helps in IntelliSence, debugging and code browsing of the programming code in the visual studio. To run the code click on Local Windows Debugger. Wait for some seconds and the web camera of your PC will open. (Press Esc to close the camera.) If you get the output then it means you have successfully installed and linked OpenCV to Visual Studio. Hope you enjoyed learning how to Install OpenCV C with Visual Studio.

CMake is a powerful and robust build system. You specify what you want done, not how to do it. CMake then takes that information and generates the files needed to build the system. For example, CMake can generate solution (.sln) and project files (.vcxproj) that Visual Studio and Visual Studio Code use on Windows. Similar capabilities are available for every other popular IDE. It can even create make files if you want to do everything from the command line. Because it can be called from the command line, it integrates well with continuous integration/continuous build systems.

You can specify the build tools that you want to use; for example, you can use MSVC or LLVM on Windows, and gnu or LLVM on Unix-like systems, including Linux, OSX, and MSYS or MinGW. Aside from specifying the tools to use, no other changes are required to the CMake specification files. You will see this when I port my project from Windows using the Visual Studio build tools to Linux using the gnu build tools.

With CMake, you can download, build, and use a large number of tools. I will show one example of this when I use Google Test in this project. Just about any tool that can be downloaded from the internet, and which provides CMake files for building, can be used.

Installing the Needed Tools

I will start the project on Windows using VS Code and the Visual Studio Build Tools, but if you wish, you can start with a different IDE, or even a different operating system. In a later article, I will discuss using the gnu tools on Linux (Ubuntu).

So let’s begin.

Installing Visual Studio Code and Extensions

On Windows, the latest version of Visual Studio Code is available on its download page. Select the appropriate version; click on the Windows button for the x64 version, or one of the ARM links for ARM if that is applicable to you. The download will begin. When it is completed, run the downloaded file.

Next, we need two VSCode extensions. Start VS Code and display the extensions panel (select View → Extensions from the main menu). In the search box, enter C++. A number of C and C++ extensions are displayed. You want the one called C++. Make sure it is from Microsoft. This extension provides Intellisense, debugging, and browsing capabilities. Click on the Install button to install it.

The second extension is CMake Tools. Search for and install it.

Installing Visual Studio Build Tools

We need the build tools provided by Visual Studio. Don’t worry, we aren’t installing Visual Studio, just the build tools.

On the Visual Studio downloads page, move down into the All Downloads section. As I write this, the current version of Visual Studio is 2019, so I will be referring to it in this section. If a later version is available, use that instead. Select Tools for Visual Studio 2019. Click on the Download button for Build Tools for Visual Studio 2019. Download and save the file. When the download has completed, open the file. This starts Visual Studio Installer. Again, don’t worry, we are not installing Visual Studio, just the build tools. When the installer window opens select only the build tools. After some time (several minutes), the install will complete. Close the installer.

Open the Windows Start menu and start Developer Command Prompt for VS 2019; do not open the standard command prompt or Powershell. At the command prompt, enter:

The following should be displayed, although the version number may be different:

If the message says that it cannot find CMake, then the build tools did not install correctly.

You will almost always be starting VS Code from the command line of Developer Command Prompt, so you will probably want to add it to the Productivity section of the Start menu.

Installing Git

We will need git. If you have done any development work, you probably already have it installed. If not, Git for Windows is available here.

A Simple C++ Program With Library

We will start by creating a simple C++ program with a simple library. You can perform similar steps, with slight modifications, if you are on Linux or any other Unix-like system. To support the program, we will create a directory structure and start VS Code as follows:

Open a Developer Command Prompt. Enter:

In the Explorer list in VS Code, select the hello/include directory and create a new file called hello.h. Place the following code in that file and save it:

Again in the Explorer list, select hello/src and create a new file called hello.cpp. Place the following code in that file and save it:

That is all the code we need for our library. Now create the program to use the library. In the Explorer list, select the apps directory and create a new file called main.cpp. Place the following code in that file and save it:

To build the library and program, we will use CMake. There are many examples of CMake on the internet, many of which are outdated or just plain bad. For this program and library, I am following Modern CMake by Henry Schreiner and others.

In the Explorer list, select VSCODE-CMAKE-HELLO in VS Code and create a new file. Call it CMakeLists.txt. Enter the following and save the file:

In the Explorer list, select apps and create a new file. Call it CMakeLists.txt. Enter the following and save the file:

Create a file called CMakeLists.txt in the hello directory and place the following code in it:

Using CMake With Visual Studio Code

Look at the status bar on the VS Code window. If it looks similar to this:

then terminate and restart VS Code. The status bar should now look like this:

Can You Run C Code In Visual Studio

From left to right, master* indicates that you are editing the git master branch and that changes have been made. The symbols and 0s indicate that there are currently no errors in workspace. Next is a button that will run CMake (CMake: [Debug]). No Kit Selected indicates that the build tools have not yet been selected; we will get to them in a moment. Following that is a Build button, the default target, a bug button that will run the application in debug mode, and a button that will run the application without starting the debugger. The remainder of the status bar provides other information that we are not currently concerned with.

We first have to run CMake to create the build files. Click on the CMake: [Debug] button. The first time you do so, a list of build tool kits is displayed below the main menu. Select either Unspecified, or Visual Studio Build Tools 2019 Release - amd64. The No Kit Selected text in the status bar will change to [Visual Studio Build Tools 2019 Release - amd64], and a list of CMake configurations are displayed: Debug, Release, MinSizeRel, and RelWithDebInfo.

Select Debug. This will execute CMake and generate a Visual Studio solution file (.sln) and Visual Studio project files (.vcxproj) if there are no errors. If there are errors, then something is not right with the CMakeLists.txt files or the C++ source files.

If you selected any of the other CMake actions, the executable, library, and debug related files would be placed in other subdirectories. For example, if you build release versions, they will be placed in build/Release.

The first time you run debugging by either clicking on the Bug button, or by selecting Run → Start Debugging, a list of build environments will be displayed just below the main menu. Select C++ (Windows).

To do a clean and rebuild, all we have to do is delete the build directory and all of its contents, then run CMake and Build.

Debugging

After a debug build, you can debug main.exe by clicking on the bug button in the status bar. Alternatively, you can select Run → Start Debugging from the main menu. In the latter case, the first time you do this, a list of debug environments is displayed. Select C++ (Windows). If the active file in VS Code is a C++ source file, a list of configurations is then displayed. You can select either cl.exe - Build and debug active file or Default configuration. If a different type of file is active, such as CMakeLists.txt, then the configuration list is not displayed.

In either case, a file called launch.json is added to the .vscode directory. Open that file and change the program to ${workspaceFolder}/build/apps/Debug/main.exe

Now you can run debug from either the bug button or the menu item.

Summary and What’s Next

This article discussed how to create a C++ project containing a program called main and a library called hello with Visual Studio Code using CMake. How to debug the program is also discussed.

There is still much to do, but that will be discussed in the following articles:

Adding GoogleTest to the project.

UPDATES

The code in hello.cpp was updated to correct a typo. Thanks Vlad T. for pointing that out.

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What you need to do to run a program depends on what you're starting from, what type of program, app, or service it is, and whether you want to run it under the debugger or not. In the simplest case, when you have a project open in Visual Studio, build and run it by pressing Ctrl+F5 (Start without debugging) or F5 (Start with debugging), or press the green arrow (Start Button) on the main Visual Studio toolbar.

Starting from a project

If you have a C# project (.csproj file), then you can run it, if it is a runnable program. If a project contains a C# file with a Main method, and its output is an executable (EXE), then most likely it will run if it builds successfully.

If you already have the code for your program in a project in Visual Studio, open the project. To open the project, double-click or tap on the .csproj from the Windows File Explorer, or from Visual Studio, choose Open a project, browse to find the project (.csproj) file, and choose the project file.

After the projects loads in Visual Studio, press Ctrl+F5 (Start without debugging) or use the green Start button on the Visual Studio toolbar to run the program. If there are multiple projects, the one with the Main method must be set as the startup project. To set the startup project, right-click on a project node, and choose Set as startup project.

Visual Studio attempts to build and run your project. If there are build errors, you see the build output in the Output window and the errors in the Error List window.

If the build succeeds, the app runs in a way that's appropriate for the type of project. Console apps run in a terminal window, Windows desktop apps start in a new window, web apps start in the browser (hosted by IIS Express), and so on.

Starting from code

If you're starting from a code listing, code file, or a small number of files, first make sure the code you want to run is from a trusted source and is a runnable program. If it has a Main method, it is likely intended as a runnable program that you can use the Console App template to create a project to work with it in Visual Studio.

Code listing for a single file

Start Visual Studio, open an empty C# console project, select all the code in the .cs file that's in the project already, and delete it. Then, paste the contents of your code into the .cs file. When you paste the code, overwrite or delete the code that was there before. Rename the file to match the original code.

Code listings for a few files

Start Visual Studio, open an empty C# console project, select all the code in the .cs file that's in the project already, and delete it. Then, paste the contents of the first code file into the .cs file. Rename the file to match the original code.

For a second file, right-click on the project node in Solution Explorer to open the shortcut menu for the project, and choose Add > Existing Item (or use the key combination Shift+Alt+A), and select the code files.

Multiple files on disk

Create a new project of the appropriate type (use C# Console App if you're not sure).
Right-click on the project node, se Add > Existing Item to select the files and import them into your project.

Starting from a folder

When you're working with a folder of many files, first see if there's a project or solution. If the program was created with Visual Studio, you should find a project file or a solution file. Look for files with the .csproj extension or .sln extension and in the Windows File Explorer, double-click on one of them to open them in Visual Studio. See Starting from a Visual Studio solution or project.

If you don't have a project file, such as if the code was developed in another development environment, then open the top-level folder by using the Open folder method in Visual Studio. See Develop code without projects or solutions.

Starting from a GitHub or Azure DevOps repo

If the code you want to run is in GitHub or in an Azure DevOps repo, you can use Visual Studio to open the project directly from the repo. See Open a project from a repo.

Run the program

To start the program, press the green arrow (Start button) on the main Visual Studio toolbar, or press F5 or Ctrl+F5 to run the program. When you use the Start button, it runs under the debugger. Visual Studio attempts to build the code in your project and run it. If that succeeds, great! But if not, continue reading for some ideas on how to get it to build successfully.

Troubleshooting

Your code might have errors, but if the code is correct, but just depends on some other assemblies or NuGet packages, or was written to target a different version of .NET, you might be able to easily fix it.

Add references

To build properly, the code must be correct and have the right references set up to libraries or other dependencies. You can look at the red squiggly lines and at the Error List to see if the program has any errors, even before you compile and run it. If you're seeing errors related to unresolved names, you probably need to add a reference or a using directive, or both. If the code references any assemblies or NuGet packages, you need to add those references in the project.

Visual Studio tries to help you identify missing references. When a name is unresolved, a light bulb icon appears in the editor. If you click the light bulb, you can see some suggestions on how to fix the issue. Fixes might be to:

add a using directive
add a reference to an assembly, or
install a NuGet package.

Missing using directive

For example, in the following screen, you can choose to add using System; to the start of the code file to resolve the unresolved name Console:

Missing assembly reference

.NET references can be in the form of assemblies or NuGet packages. Usually, if you find source code, the publisher or author will explain what assemblies are required and what packages the code depends on. To add a reference to a project manually, right-click on the References node in the Solution Explorer, choose Add Reference, and locate the required assembly.

You can find assemblies and add references by following the instructions in Add or remove references by using the reference manager.

Missing NuGet package

If Visual Studio detects a missing NuGet package, a light bulb appears and gives you the option to install it:

If that doesn't solve the issue and Visual Studio can't locate the package, try searching for it online. See Install and use a NuGet package in Visual Studio.

Use the right version of .NET

Because different versions of the .NET Framework have some degree of backward compatibility, a newer framework might run code written for an older framework without any modifications. But, sometimes you need to target a specific framework. You might need to install a specific version of the .NET Framework or .NET Core, if it's not already installed. See Modify Visual Studio.

To change the target framework, see Change the target framework. For more information, see Troubleshooting .NET Framework targeting errors.

Next steps

Explore the Visual Studio development environment by reading Welcome to the Visual Studio IDE.

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