Visual studio code microsoft

03.09.202203.09.2022 admin 0 Comments

Visual studio code microsoft

Узнайте, как использовать редактор кода

В этом 10-минутном введении, посвященном редактору кода в Visual Studio, мы добавим код в файл, чтобы рассмотреть некоторые способы, упрощающие написание, понимание кода и навигацию по нему в Visual Studio.

Установите Visual Studio бесплатно со страницы скачиваемых материалов Visual Studio, если еще не сделали этого.

Эта статья предполагает, что вы уже знакомы с языком программирования. В противном случае рекомендуется сначала посмотреть одно из кратких руководств по языкам программирования Python или C# либо по созданию консольного приложения с помощью Visual Basic или C++.

Чтобы выполнять действия, описанные в этой статье, выберите нужные параметры C# для Visual Studio. Сведения о настройке параметров для интегрированной среды разработки (IDE) вы найдете в этой статье.

Создание файла кода

Для начала создайте файл и добавьте в него код.

Запустите Visual Studio. Нажмите клавишу ESC или нажмите Продолжить без кода в окне запуска, чтобы открыть среду разработки.

В меню Файл в строке меню выберите пункты Создать>Файл.

В диалоговом окне Новый файл в разделе Общие выберите Класс Visual C# и нажмите кнопку Открыть.

Новый файл открывается в редакторе с каркасом класса C#. (Обратите внимание, что нам не нужно создавать полный проект Visual Studio, чтобы получить некоторые преимущества редактора кода. Вам нужен только файл кода!)

Запустите Visual Studio. Нажмите клавишу ESC или щелкните команду Продолжить без кода в окне запуска, чтобы открыть среду разработки.

В меню Файл в строке меню выберите элементы Создать>Файл или нажмите клавиши CTRL+N.

В диалоговом окне Новый файл в разделе Общие выберите Класс Visual C# и нажмите кнопку Открыть.

Новый файл открывается в редакторе с каркасом класса C#.

Использование фрагментов кода

Visual Studio предоставляет удобные фрагменты кода, позволяющие быстро и легко создавать часто используемые блоки кода. Фрагменты кода доступны для различных языков программирования, включая C#, Visual Basic и C++.

Давайте добавим фрагмент void Main C# в файл.

Два раза нажмите клавишу TAB, чтобы вставить фрагмент кода.

Для разных языков программирования доступны различные фрагменты кода. Вы можете просмотреть фрагменты кода, доступные для используемого языка, выбрав Изменить>IntelliSense>Вставить фрагмент и указав папку вашего языка. Для C# список выглядит следующим образом.

Два раза нажмите клавишу TAB, чтобы вставить фрагмент кода.

Для разных языков программирования доступны соответствующие фрагменты кода. Вы можете просмотреть фрагменты кода, доступные для используемого языка. Для этого выберите элементы Изменить>IntelliSense>Вставить фрагмент или нажмите клавиши CTRL+K и CTRL+X, а затем укажите папку для своего языка программирования. Для C# список фрагментов кода выглядит следующим образом.

Список включает фрагменты кода для создания класса, конструктора, цикла for, операторов if и switch и многое другое.

Закомментирование кода

Панель инструментов, которая находится в строке кнопок под строкой меню в Visual Studio, поможет повысить продуктивность написания кода. Например, можно переключить режим завершения IntelliSense (IntelliSense — это помощник в написании кода, который отображает список подходящих методов и многое другое), увеличить или уменьшить отступ строки или закомментировать код, который вы не хотите компилировать. В этом разделе мы закомментируем код.

Символы комментария C# // добавляются в начало каждой выбранной строки, чтобы закомментировать код.

Панель инструментов текстового редактора, которая представляет строку с кнопками под строкой меню в Visual Studio, делает написание кода более продуктивным. Например, вы можете переключить режим завершения IntelliSense, увеличить либо уменьшить отступ для строк или закомментировать фрагмент кода, который не нужно компилировать.

Давайте закомментируем некоторую часть кода.

Символы комментария C# // добавляются в начало каждой выбранной строки, чтобы закомментировать код.

Если нужно раскомментировать строки, выберите их, а затем нажмите кнопку Раскомментировать выбранные строки на панели инструментов текстового редактора. Если вы предпочитаете использовать клавиатуру, нажмите клавиши CTRL+K, CTRL+U.

Свертывание блоков кода

Просмотр определений символов

Щелкните правой кнопкой мыши любой из экземпляров string и выберите пункт Показать определение в контекстном меню. Или нажмите Alt+F12.

Закройте окно просматриваемого определения, щелкнув небольшое поле со знаком «x» в его правом верхнем углу.

В редакторе Visual Studio можно легко проверить определение типа, метода или переменной. Один из способов — перейти к файлу, который содержит определение. Для этого выберите команду Перейти к определению или нажмите клавишу F12 в любом месте, где указана ссылка на этот символ. Сделать это еще быстрее и даже без перемещения фокуса с кода можно, щелкнув команду Показать определение.

Щелкните правой кнопкой мыши любой из экземпляров string и выберите пункт Показать определение в контекстном меню. Или нажмите клавиши ALT+F12.

Закройте окно просматриваемого определения, щелкнув небольшое поле со знаком Х справа в верхнем углу.

Использование IntelliSense для завершения слов

Технология IntelliSense крайне полезна при написании кода. Она может отображать сведения о доступных членах типа или сведения о параметрах для различных перегрузок метода. Вы также можете использовать IntelliSense для завершения слова после того, как ввели достаточно знаков для однозначного его определения. Давайте добавим строку кода для вывода упорядоченных строк в окне консоли — это стандартное место для отображения выходных данных программы.

Чтобы вставить оставшуюся часть слова query с помощью функции завершения слов IntelliSense, нажмите клавишу Tab.

Давайте добавим строку кода для вывода упорядоченных строк в окне консоли — это стандартное место для отображения выходных данных программы.

Чтобы вставить оставшуюся часть слова query с помощью функции завершения слов IntelliSense, нажмите клавишу TAB.

Рефакторинг имени

Поместите курсор на определение переменной _words и выберите пункт Переименовать в контекстном меню или нажмите клавиши CTRL+R, CTRL+R.

В верхней правой части редактора отображается всплывающее диалоговое окно Переименование.

Введите нужное имя words. Обратите внимание, что ссылка на words в запросе также переименовывается автоматически. Перед нажатием клавиши ВВОД установите флажок Включить комментарии во всплывающем окне Переименование.

Нажмите клавишу ВВОД.

Поместите курсор на определение переменной someWords и выберите команду Переименовать в контекстном меню или нажмите клавишу F2.

Справа в верхней части окна редактора отобразится диалоговое окно Переименование.

Введите имя unsortedWords. Вы увидите, что ссылка на unsortedWords в операторе назначения query также переименовывается автоматически. Прежде чем нажать клавишу ВВОД или щелкнуть действие Применить, установите флажок Включить комментарии во всплывающем окне Переименовать.

Нажмите клавишу ВВОД или щелкните команду Применить в диалоговом окне Переименование.

Оба вхождения someWords в коде, а также текст someWords в комментарии к коду были переименованы.

Navigate code

Visual Studio provides numerous ways to navigate code in the editor. This topic summarizes the different ways you can navigate your code, and provides links to topics that go into more detail.

Navigate Backward and Navigate Forward commands

You can use the Navigate Backward (Ctrl+—) and Navigate Forward (Ctrl+Shift+—) buttons on the toolbar to move the insertion point to previous locations, or to return to a more recent location from a previous location. These buttons retain the last 20 locations of the insertion point. These commands are also available on the View menu, under Navigate Backward and Navigate Forward.

Navigation bar

You can use the navigation bar (the drop-down boxes at the top of the code window) to navigate to code in a codebase. You can choose a type or member to go directly to it. The navigation bar appears when you edit code in a Visual Basic, C#, or C++ code base. In a partial class, members defined outside the current code file may be disabled (they appear in gray).

You can navigate around the drop-down boxes as follows:

To navigate to another project that the current file belongs to, choose it in the left drop-down.

To navigate to a class or type, choose it in the middle drop-down.

To navigate directly to a procedure or other member of a class, choose it in the right drop-down.

To shift focus from the code window to the navigation bar, press the shortcut key combination Ctrl+F2.

To shift focus from box to box on the navigation bar, press the Tab key.

To select the navigation bar item that has focus and return to the code window, press the Enter key.

To return focus from the navigation bar to the code without selecting anything, press the Esc key.

To hide the navigation bar, change the Navigation bar option in the Text Editor All Languages settings (Tools > Options > Text Editor > All Languages), or you can change the settings for individual languages.

Find all references

Finds all the references to the selected element in the solution. You can use this to check possible side-effects of a large refactoring, or to verify «dead» code. Press F8 to jump between results. For more information, see Find references in your code.

Input	Function
Keyboard	Place your text cursor somewhere inside the type name, and press Shift+F12
Mouse	Select Find All References from the right-click menu

Reference highlighting

When you click a symbol in the source code, all instances of that symbol are highlighted in the document. The highlighted symbols may include declarations and references, and many other symbols that Find All References would return. These include the names of classes, objects, variables, methods, and properties. In Visual Basic code, keywords for many control structures are also highlighted. To move to the next or the previous highlighted symbol, press Ctrl+Shift+Down Arrow or Ctrl+Shift+Up Arrow. You can change the highlighting color in Tools > Options > Environment > Fonts and Colors > Highlighted Reference.

Go To commands

Go To has the following commands, which are available in the Edit menu under Go To:

Go To Line (Ctrl+G): Move to the specified line number in the active document.

Go To All (Ctrl+T or Ctrl+,): Move to the specified line, type, file, member, or symbol.

Go To File (Ctrl+1, Ctrl+F): Move to the specified file in the solution.

Go To Recent File (Ctrl+1, Ctrl+R): Move to the specified, recently visited file in the solution.

Go To Type (Ctrl+1, Ctrl+T): Move to the specified type in the solution.

Go To Member (Ctrl+1, Ctrl+M): Move to the specified member in the solution.

Go To Symbol (Ctrl+1, Ctrl+S): Move to the specified symbol in the solution.

In Visual Studio 2017 version 15.8 and later, the following Go To navigation commands are also available:

Go To Next Issue in File (Alt+PgDn) and Go To Previous Issue in File (Alt+PgUp)

Go To Last Edit Location (Ctrl+Shift+Backspace)

See more about these commands in the Find code using Go To commands topic.

Go To Definition

Go To Definition takes you to the definition of the selected element. For more information, see Go To Definition and Peek Definition.

Input	Function
Keyboard	Place your text cursor somewhere inside the type name, and press F12
Mouse	Right-click on the type name and select Go To Definition OR press Ctrl and click on the type name

Peek Definition

Peek Definition displays the definition of the selected element in a window without navigating away from your current location in the code editor. For more information, see How to: View and edit code by using Peek Definition and Go To Definition and Peek Definition.

Input	Function
Keyboard	Place your text cursor somewhere inside the type name, and press Alt+F12
Mouse	Right-click on the type name and select Peek Definition OR press Ctrl and click on the type name (if you have the Open definition in peek view option checked)

Go To Implementation

Using Go To Implementation, you can navigate from a base class or type to its implementations. If there are multiple implementations, you will see them listed in the Find Symbol Results window:

Input	Function
Keyboard	Place your text cursor somewhere inside the type name, and press Ctrl+F12
Mouse	Right-click on the type name and select Go To Implementation

Go To Base

Using Go To Base, you can navigate up the inheritance chain of the selected element. If there are multiple results, you will see them listed in the Go To Base window:

Input	Function
Keyboard	Place your text cursor somewhere inside the type name, and press Alt+Home
Mouse	Right-click on the type name and select Go To Base

Call Hierarchy

You can view calls to and from a method in the Call Hierarchy window:

Input	Function
Keyboard	Place your text cursor somewhere inside the type name, and press Ctrl+K, Ctrl+T
Mouse	Right-click on the member name and select View Call Hierarchy

Next Method and Previous Method commands (Visual Basic)

In Visual Basic code files, use these commands to move the insertion point to different methods. Choose Edit > Next Method or Edit > Previous Method.

Structure Visualizer

To disable structure guide lines, go to Tools > Options > Text Editor > General and clear the Show structure guide lines box.

Enhanced scroll bar

You can use the enhanced scroll bar in a code window to get a bird’s-eye view of your code. In map mode, you can see previews of the code when you move the cursor up and down the scroll bar. For more information, see How to: Track your code by customizing the scroll bar.

CodeLens information

You can find info about specific code, like changes and who made those changes, references, bugs, work items, code reviews, and unit test status when you use CodeLens in the code editor. CodeLens works like a heads-up display when you use Visual Studio Enterprise with Team Foundation Server. See Find code changes and other history.

Welcome to the Visual Studio IDE

An integrated development environment (IDE) is a feature-rich program that supports many aspects of software development. The Visual Studio IDE is a creative launching pad that you can use to edit, debug, and build code, and then publish an app. Over and above the standard editor and debugger that most IDEs provide, Visual Studio includes compilers, code completion tools, graphical designers, and many more features to enhance the software development process.

The preceding image shows Visual Studio with an open project that shows key windows and their functionality:

In Solution Explorer, at upper right, you can view, navigate, and manage your code files. Solution Explorer can help organize your code by grouping the files into solutions and projects.

The central editor window, where you’ll probably spend most of your time, displays file contents. In the editor window, you can edit code or design a user interface such as a window with buttons and text boxes.

In Git Changes at lower right, you can track work items and share code with others by using version control technologies like Git and GitHub.

Editions

Visual Studio is available for Windows and Mac. Visual Studio for Mac has many of the same features as Visual Studio for Windows, and is optimized for developing cross-platform and mobile apps. This article focuses on the Windows version of Visual Studio.

There are three editions of Visual Studio: Community, Professional, and Enterprise. See Compare Visual Studio editions to learn about which features are supported in each edition.

Popular productivity features

Some popular features in Visual Studio that improve your productivity when developing software include:

Squiggles are wavy underlines that alert you to errors or potential problems in your code as you type. These visual clues help you fix problems immediately, without waiting to discover errors during build or runtime. If you hover over a squiggle, you see more information about the error. A lightbulb might also appear in the left margin showing Quick Actions you can take to fix the error.

Refactoring includes operations such as intelligent renaming of variables, extracting one or more lines of code into a new method, and changing the order of method parameters.

IntelliSense is a set of features that display information about your code directly in the editor and, in some cases, write small bits of code for you. It’s like having basic documentation inline in the editor, so you don’t have to look up type information elsewhere.

The following illustration shows how IntelliSense displays a member list for a type:

Visual Studio menus, options, and properties can seem overwhelming at times. Visual Studio search, or Ctrl+Q, is a great way to rapidly find IDE features and code in one place.

For information and productivity tips, see How to use Visual Studio search.

Collaboratively edit and debug with others in real time, regardless of your app type or programming language. You can instantly and securely share your project. You can also share debugging sessions, terminal instances, localhost web apps, voice calls, and more.

The Call Hierarchy window shows the methods that call a selected method. This information can be useful when you’re thinking about changing or removing the method, or when you’re trying to track down a bug.

CodeLens helps you find code references, code changes, linked bugs, work items, code reviews, and unit tests, without leaving the editor.

The Go To Definition feature takes you directly to the location of a function or type definition.

The Peek Definition window shows a method or type definition without opening a separate file.

Install Visual Studio

In this section, you create a simple project to try out some of the things you can do with Visual Studio. You use IntelliSense as a coding aid, debug an app to see a variable value during app execution, and change the color theme.

To get started, download Visual Studio and install it on your system. The modular installer enables you to choose and install workloads, which are groups of features needed for the programming languages or platforms you want. To follow the steps to create a program, be sure to select the .NET Core cross-platform development workload during installation.

To get started, download Visual Studio and install it on your system. In the modular installer, you choose and install workloads, which are groups of features you need for the programming languages or platforms you want. To use the following steps to create a program, be sure to select the .NET desktop development workload during installation.

When you open Visual Studio for the first time, you can sign in by using your Microsoft account or your work or school account.

Create a program

Dive in and create a simple program.

Open Visual Studio.

The start window appears with options for cloning a repo, opening a recent project, or creating a new project.

Choose Create a new project.

The Create a new project window opens and shows several project templates. A template contains the basic files and settings required for a given project type.

To find the template we want, type or enter .net core console in the search box. The list of available templates is automatically filtered based on the keywords you entered. You can further filter the template results by choosing C# from the All language drop-down list, Windows from the All platforms list, and Console from the All project types list.

Select the Console Application template, and then click Next.

In the Configure your new project window, enter HelloWorld in the Project name box, optionally change the directory location for your project files (the default locale is C:\Users\ \source\repos ), and then click Next.

In the Additional information window, verify that .NET Core 3.1 appears in the Target Framework drop-down menu, and then click Create.

Visual Studio creates the project. It’s a simple «Hello World» application that calls the Console.WriteLine() method to display the literal string «Hello World!» in the console (program output) window.

Shortly, you should see something like the following screen:

The C# code for your application shows in the editor window, which takes up most of the space. Notice that the text is automatically colorized to indicate different parts of the code, such as keywords and types. In addition, small, vertical dashed lines in the code indicate which braces match one another, and line numbers help you locate code later. You can choose the small, boxed minus signs to collapse or expand blocks of code. This code outlining feature lets you hide code you don’t need, helping to minimize onscreen clutter. The project files are listed on the right side in a window called Solution Explorer.

There are other menus and tool windows available, but let’s move on for now.

Now, start the app. You can do this by choosing Start Without Debugging from the Debug menu on the menu bar. You can also press Ctrl+F5.

Start without Debugging menu item.» data-linktype=»relative-path»>

Visual Studio builds the app, and a console window opens with the message Hello World!. You now have a running app!

To close the console window, press any key on your keyboard.

Let’s add some more code to the app. Add the following C# code before the line that says Console.WriteLine(«Hello World!»); :

This code displays What is your name? in the console window, and then waits until the user enters some text followed by the Enter key.

Change the line that says Console.WriteLine(«Hello World!»); to the following code:

Run the app again by selecting Debug > Start Without Debugging or by pressing Ctrl+F5.

Visual Studio rebuilds the app, and a console window opens and prompts you for your name.

Enter your name in the console window and press Enter.

Press any key to close the console window and stop the running program.

Start Visual Studio. The start window appears with options for cloning a repo, opening a recent project, or creating a new project.

Choose Create a new project.

The Create a new project window opens and shows several project templates. A template contains the basic files and settings required for a given project type.

To find a template, you can type or enter keywords in the search box. The list of available templates filters based on the keywords you enter. You can further filter the template results by choosing C# from the All languages dropdown list, Windows from the All platforms list, and Console from the All project types list.

Select the Console Application template, and then select Next.

In the Configure your new project window, enter HelloWorld in the Project name box. Optionally, change the project directory location from the default location of C:\Users\ \source\repos, and then select Next.

In the Additional information window, verify that .NET 6.0 appears in the Target Framework drop-down menu, and then select Create.

Visual Studio creates the project. The program is a simple «Hello World» application that calls the Console.WriteLine() method to display the string Hello, World! in a console window.

The project files appear on the right side of the Visual Studio IDE, in a window called the Solution Explorer. In the Solution Explorer window, select the Program.cs file. The C# code for your app opens in the central editor window, which takes up most of the space.

The code is automatically colorized to indicate different parts, such as keywords and types. Line numbers help you locate code.

Small, vertical dashed lines in the code indicate which braces match one another. You can also choose small, boxed minus or plus signs to collapse or expand blocks of code. This code outlining feature lets you hide code you don’t need to see, helping to minimize onscreen clutter.

Many other menus and tool windows are available.

Start the app by choosing Debug > Start Without Debugging from the Visual Studio top menu. You can also press Ctrl+F5.

Start without Debugging menu item.» data-linktype=»relative-path»>

Visual Studio builds the app, and a console window opens with the message Hello, World!. You now have a running app!

To close the console window, press any key.

Let’s add some more code to the app. Add the following C# code before the line that says Console.WriteLine(«Hello World!»); :

This code displays What is your name? in the console window, and then waits until the user enters some text.

Change the line that says Console.WriteLine(«Hello World!»); to the following line:

Run the app again by selecting Debug > Start Without Debugging or pressing Ctrl+F5.

Visual Studio rebuilds the app, and a console window opens and prompts you for your name.

Type your name in the console window and press Enter.

Press any key to close the console window and stop the running program.

Use refactoring and IntelliSense

Let’s look at a couple of the ways that refactoring and IntelliSense can help you code more efficiently.

First, rename the name variable:

Double-click the name variable, and type the new name for the variable, username.

A box appears around the variable, and a light bulb appears in the margin.

Select the light bulb icon to show the available Quick Actions. Select Rename ‘name’ to ‘username’.

The variable is renamed across the project, which in our case is only two places.

A box displays the members of the DateTime class. The description of the currently selected member also displays in a separate box.

Below that line, enter the following lines of code:

Console.Write is different from Console.WriteLine in that it doesn’t add a line terminator after it prints. That means that the next piece of text that’s sent to the output will print on the same line. You can hover over each of these methods in your code to see their descriptions.

Select the screwdriver icon to see available suggestions from Visual Studio. This case shows the Inline temporary variable refactoring to remove a line of code without changing the overall code behavior.

Select Inline temporary variable to refactor the code.

Run the program again by pressing Ctrl+F5. The output looks something like this:

Debug code

When you write code, you should run it and test it for bugs. Visual Studio’s debugging system lets you step through code one statement at a time and inspect variables as you go. You can set breakpoints that stop execution of the code at a particular line, and observe how the variable value changes as the code runs.

Set a breakpoint to see the value of the username variable while the program is running.

Set a breakpoint on the line of code that says Console.WriteLine($»\nHello !»); by clicking in the far-left margin, or gutter, next to the line. You can also select the line of code and then press F9.

A red circle appears in the gutter, and the line is highlighted.

Start debugging by selecting Debug > Start Debugging or pressing F5.

When the console window appears and asks for your name, enter your name.

The focus returns to the Visual Studio code editor, and the line of code with the breakpoint is highlighted in yellow. The yellow highlight means that this line of code will execute next. The breakpoint makes the app pause execution at this line.

Hover your mouse over the username variable to see its value. You can also right-click on username and select Add Watch to add the variable to the Watch window, where you can also see its value.

Press F5 again to finish running the app.

For more information about debugging in Visual Studio, see the Debugger feature tour.

Customize Visual Studio

You can personalize the Visual Studio user interface, including changing the default color theme. To change the color theme:

On the menu bar, choose Tools > Options to open the Options dialog.

On the Environment > General options page, change the Color theme selection to Dark, and then choose OK.

The color theme for the entire IDE changes to Dark.

On the menu bar, choose Tools > Options to open the Options dialog.

On the Environment > General options page, change the Color Theme selection to Blue or Light, and then select OK.

The color theme for the entire IDE changes accordingly. The following screenshot shows the Blue theme:

To learn about other ways you can personalize the IDE, see Personalize Visual Studio.

Next steps

Explore Visual Studio further by following along with one of these introductory articles:

Cover the basics in this Learn module: Introduction to Visual Studio.

Get acquainted with the code editor in Learn to use the code editor.

Learn how Visual Studio organizes code in Learn about projects and solutions.

If you’re ready to dive into more coding, one of the following language-specific quickstarts is a good next step:

Another good place to start with coding is a tutorial:

Debugging techniques and tools to help you write better code

Fixing bugs and errors in your code can be a time-consuming—and sometimes frustrating—task. It takes time to learn how to debug effectively, but a powerful IDE like Visual Studio can make your job a lot easier. An IDE can help you fix errors and debug your code more quickly, and not just that, but it can also help you write better code with fewer bugs. Our aim in this article is to give you a holistic view of the «bug-fixing» process, so you will know when to use the code analyzer, when to use the debugger, how to fix exceptions, and how to code for intent. If you already know you need to use the debugger, see First look at the debugger.

In this article, we talk about leveraging the IDE to make your coding sessions more productive. We touch on several tasks, such as:

Prepare your code for debugging by leveraging the IDE’s code analyzer

How to fix exceptions (run-time errors)

How to minimize bugs by coding for intent (using assert)

When to use the debugger

To demonstrate these tasks, we show a few of the most common types of errors and bugs that you’ll encounter when trying to debug your apps. Although the sample code is C#, the conceptual information is generally applicable to C++, Visual Basic, JavaScript, and other languages supported by Visual Studio (except where noted). The screenshots are in C#.

Create a sample app with some bugs and errors in it

The following code has some bugs that you can fix using the Visual Studio IDE. The app here is a simple app that simulates getting JSON data from some operation, deserializing the data to an object, and updating a simple list with the new data.

To create the app:

You must have Visual Studio installed and the .NET Core cross platform development workload installed.

If you haven’t already installed Visual Studio, go to theВ Visual Studio downloadsВ page to install it for free.

If you need to install the workload but already have Visual Studio, click Tools > Get Tools and Features. The Visual Studio Installer launches. Choose the .NET Core cross platform development workload, then choose Modify.

Open Visual Studio.

Visual Studio creates the console project, which appears in Solution Explorer in the right pane.

Replace the default code in the project’s Program.cs file with the sample code below.

Find the red and green squiggles!

Before you try to start the sample app and run the debugger, check the code in the code editor for red and green squiggles. These represent errors and warnings that are identified by the IDE’s code analyzer. The red squiggles are compile-time errors, which you must fix before you can run the code. The green squiggles are warnings. Although you can often run your app without fixing the warnings, they can be a source of bugs and you often save yourself time and trouble by investigating them. These warnings and errors also show up in the Error List window, if you prefer a list view.

In the sample app, you see several red squiggles that you need to fix, and one green one that you’ll look at. Here is the first error.

To fix this error, you’ll look at another feature of the IDE, represented by the light bulb icon.

Check the light bulb!

When you click this item, Visual Studio adds the using System.Text statement at the top of the Program.cs file, and the red squiggle disappears. (When you’re not sure what a suggested fix will do, choose the Preview changes link on the right before applying the fix.)

The preceding error is a common one that you usually fix by adding a new using statement to your code. There are several common, similar errors to this one such as The type or namespace `Name` cannot be found. These kinds of errors may indicate a missing assembly reference (right-click the project, choose Add > Reference), a misspelled name, or a missing library that you need to add (for C#, right-click the project and choose Manage NuGet Packages).

Fix the remaining errors and warnings

There are a few more squiggles to look at in this code. Here, you see a common type conversion error. When you hover over the squiggle, you see that the code is trying to convert a string to an int, which is not supported unless you add explicit code to make the conversion.

To fix this error, change the points member of the User class from this:

The red squiggly lines in the code editor go away.

Next, hover over the green squiggle in the declaration of the points data member. The code analyzer tells you the variable is never assigned a value.

Typically, this represents a problem that needs to be fixed. However, in the sample app you are in fact storing data in the points variable during the deserialization process, and then adding that value to the totalpoints data member. In this example, you know the intent of the code and can safely ignore the warning. However, if you want to eliminate the warning, you can replace the following code:

The green squiggle goes away.

Fix an exception

When you have fixed all the red squiggles and resolved—or at least investigated—all the green squiggles, you are ready to start the debugger and run the app.

Press F5 (Debug > Start Debugging) or the Start Debugging button in the Debug toolbar.

At this point, the sample app throws a SerializationException exception (a runtime error). That is, the app chokes on the data that it is trying to serialize. Because you started the app in debug mode (debugger attached), the debugger’s Exception Helper takes you right to the code that threw the exception and gives you a helpful error message.

When you hit an exception, you need to ask (and answer) a couple of questions:

Is this exception just a bug that you can fix? Or,

Is this exception something that your users might encounter?

If it’s the former, fix the bug. (In the sample app, that means fix the bad data.) If it’s the latter, you might need to handle the exception in your code using a try/catch block (we look at other possible strategies in the next section). In the sample app, replace the following code:

A try/catch block has some performance cost, so you’ll only want to use them when you really need them, that is, where (a) they might occur in the release version of the app, and where (b) the documentation for the method indicates that you should check for the exception (assuming the documentation is complete!). In many cases, you can handle an exception appropriately and the user will never need to know about it.

Here are a couple of important tips for exception handling:

For unfamiliar functions that you include in your app, especially those interacting with external data (such as a web request), check the documentation to see what exceptions the function is likely to throw. This can be critical information for proper error handling and for debugging your app.

Clarify your code intent by using assert

Click the Restart button in the Debug Toolbar (Ctrl + Shift + F5). This restarts the app in fewer steps. You see the following output in the console window.

You can see something in this output that is not quite right. name and lastname for the third record are blank!

By adding assert statements like this to your functions during the development process, you can help specify the intent of your code. In the preceding example, we specify the following:

By specifying intent in this way, you enforce your requirements. This is a simple and handy method that you can use to surface bugs during development. ( assert statements are also used as the main element in unit tests.)

Click the Restart button in the Debug Toolbar (Ctrl + Shift + F5).

The assert code is active only in a Debug build.

The assert error tells you that there’s a problem that you need to investigate. assert can cover many scenarios where you don’t necessarily see an exception. In this example, the user won’t see an exception, and a null value gets added as firstname in your list of records. This may cause problems later on (such as you see in the console output) and might be harder to debug.

During the debugging process, it’s good to keep a particular assert statement until you know you need to replace it with an actual code fix. Let’s say you decide that the user might encounter the exception in a release build of the app. In that case, you must refactor code to make sure that your app doesn’t throw a fatal exception or result in some other error. So, to fix this code, replace the following code:

By using this code, you fulfill your code requirements and make sure that a record with a firstname or lastname value of null is not added to the data.

For the preceding statements, your intent is that you load existing data ( db ) and retrieve new data ( users ) before updating anything.

The preceding code is useful if you want to specify the following intent: a new point value greater than zero (0) is required to update the user’s record.

Inspect your code in the debugger

OK, now that you’ve fixed everything critical that’s wrong with the sample app, you can move onto other important stuff!

We showed you the debugger’s Exception Helper, but the debugger is a much more powerful tool that also lets you do other things like step through your code and inspect its variables. These more powerful capabilities are useful in many scenarios, especially the following:

You are trying to isolate a runtime bug in your code, but are unable to do it using methods and tools previously discussed.

You want to validate your code, that is, watch it while it runs to make sure it is behaving in the way you expect and doing what you want it to.

It is instructive to watch your code while it runs. You can learn more about your code this way and can often identify bugs before they manifest any obvious symptoms.

To learn how to use the essential features of the debugger, see Debugging for absolute beginners.

Fix performance issues

Bugs of another kind include inefficient code that causes your app to run slowly or to use too much memory. Generally, optimizing performance is something you do later in your app development. However, you can run into performance issues early (for example, you see that some part of your app is running slow), and you may need to test your app with the profiling tools early on. For more information about profiling tools such as the CPU Usage tool and the Memory Analyzer, see First look at the profiling tools.

Next steps

In this article, you’ve learned how to avoid and fix many common bugs in your code and when to use the debugger. Next, learn more about using the Visual Studio debugger to fix bugs.

Develop code in Visual Studio without projects or solutions

You can open code from nearly any type of directory-based project into Visual Studio without the need for a solution or project file. This means you can, for example, clone a repo on GitHub, open it directly into Visual Studio, and begin developing, without having to create a solution or project. If needed, you can specify custom build tasks and launch parameters through simple JSON files.

After you open your code files in Visual Studio, Solution Explorer displays all the files in the folder. You can click on any file to begin editing it. In the background, Visual Studio starts indexing the files to enable IntelliSense, navigation, and refactoring features. As you edit, create, move, or delete files, Visual Studio tracks the changes automatically and continuously updates its IntelliSense index. Code will appear with syntax colorization and, in many cases, include basic IntelliSense statement completion.

If you’re looking for information that’s specific to VS Code, visit the Getting started with Visual Studio Code page.

Open any code

You can open code into Visual Studio in the following ways:

On the Visual Studio menu bar, choose File > Open > Folder, and then browse to the code location.

On the context (right-click) menu of a folder containing code, choose the Open in Visual Studio command.

Choose the Open Folder link on the start window.

If you are a keyboard user, press Ctrl+Shift+Alt+O in Visual Studio.

Open code from a cloned GitHub repo.

To open code from a cloned GitHub repo

The following example shows how to clone a GitHub repo and then open its code in Visual Studio. To follow this procedure, you must have a GitHub account and Git for Windows installed on your system. See Create a GitHub account to use with Visual Studio and Git for Windows for more information.

Go to the repo you want to clone on GitHub.

Choose the Clone or Download button and then choose the Copy to Clipboard button in the dropdown menu to copy the secure URL for the GitHub repo.

Use Git in Visual Studio

As of Visual Studio 2019 version 16.8, we introduced a new, streamlined Git interface that you can use to interact with your files on GitHub. To learn more, visit the Visual Studio version control docs.

Use Team Explorer in Visual Studio

You can still use Team Explorer in Visual Studio 2022 and in Visual Studio 2019 version 16.8 and later. However, you might find it easier to use the new Git experience. For more information, see How Visual Studio makes version control easy with Git.

In Visual Studio, choose the Team Explorer tab to open Team Explorer. If you don’t see the tab, open it from View > Team Explorer.

In Team Explorer, under the Local Git Repositories section, choose the Clone command and then paste the URL of the GitHub page into the text box.

Choose the Clone button to clone the project’s files to a local Git repository. Depending on the size of the repo, this process could take several minutes.

After the repo has been cloned to your system, in Team Explorer, choose the Open command on the context (right-click) menu of the newly cloned repo.

Choose the Show Folder View command to view the files in Solution Explorer.

You can now browse folders and files in the cloned repo, and view and search the code in the Visual Studio code editor, complete with syntax colorization and other features.

Run and debug your code

You can debug your code in Visual Studio without a project or solution! To debug some languages, you may need to specify a valid startup file in the codebase, such as a script, executable, or project. The drop-down list box next to the Start button on the toolbar lists all of the startup items that Visual Studio detects, as well as items you specifically designate. Visual Studio runs this code first when you debug your code.

Configuring your code to run in Visual Studio differs depending on what kind of code it is, and what the build tools are.

Codebases that use MSBuild

MSBuild-based codebases can have multiple build configurations that appear in the Start button’s drop-down list. Select the file that you want to use as the startup item, and then choose the Start button to begin debugging.

For C# and Visual Basic codebases, you must have the .NET desktop development workload installed. For C++ codebases, you must have the Desktop development with C++ workload installed.

Codebases that use custom build tools

If your codebase uses custom build tools, then you must tell Visual Studio how to build your code using build tasks that are defined in a .json file. For more information, see Customize build and debug tasks.

Codebases that contain Python or JavaScript code

If your codebase contains Python or JavaScript code, you don’t have to configure any .json files, but you do have to install the corresponding workload. You must also configure the startup script:

Install the Node.js development or Python development workload by choosing Tools > Get Tools and Features, or by closing Visual Studio and running the Visual Studio Installer.

In Solution Explorer, on the right-click or context menu of a JavaScript or Python file, choose the Set as Startup Item command.

Choose the Start button to begin debugging.

Codebases that contain C++ code

For information about opening C++ code without solutions or projects in Visual Studio, see Open Folder projects for C++.

Codebases that contain a Visual Studio project

If your code folder contains a Visual Studio project, you can designate the project as the startup item.

The Start button’s text changes to reflect that the project is the startup item.