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Immediate Window

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The Immediate window is used to evaluate expressions, execute statements, print variable values, and so forth. It allows you to enter expressions to be evaluated or executed by the development language during debugging. To display the Immediate window, open a project for editing, then choose Windows from the Debug menu and select Immediate.

You can use this window to issue individual Visual Studio commands. The available commands include EvaluateStatement, which can be used to assign values to variables. The Immediate window also supports IntelliSense.

Displaying the Values of Variables

This window can be particularly useful while debugging an application. For example, to check the value of a variable varA, you can use the Print Command:

>Debug.Print varA

The question mark (?) is an alias for Debug.Print, so this command can also be written:

>? varA

Both versions of this command will return the value of the variable varA.

Note

To issue a Visual Studio command in the Immediate window, you must preface the command with a greater than sign (>). To enter multiple commands, switch to the Command window.

Design Time Expression Evaluation

You can use the Immediate window to execute a function or subroutine at design time.

To execute a function at design time

  1. Copy the following code into a Visual Basic console application:

    Module Module1

    Sub Main()
        MyFunction(5)
    End Sub

    Function MyFunction(ByVal input as Integer) As Integer
        Return input * 2
    End Function

End Module

  2. On the Debug menu, click Windows, and then click Immediate.

  3. Type ?MyFunction(2) in the Immediate window and press Enter.

    The Immediate window will run MyFunction and display 4.

If the function or subroutine contains a breakpoint, Visual Studio will break execution at the appropriate point. You can then use the debugger windows to examine your program state. For more information see Walkthrough: Debugging at Design Time and Breaking During Function Evaluation in the Visual Studio Debugger.

You cannot use design time expression evaluation in project types that require starting up an execution environment, including Visual Studio Tools for Office projects, Web projects, Smart Device projects, and SQL projects.

Design Time Expression Evaluation in Multi-Project Solutions

When establishing the context for design time expression evaluation, Visual Studio references the currently selected project in Solution Explorer. If no project is selected in Solution Explorer, Visual Studio attempts to evaluate the function against the startup project. If the function cannot be evaluated in the current context, you will receive an error message. If you are attempting to evaluate a function in a project that is not the startup project for the solution and you receive an error, try selecting the project in Solution Explorer and attempt the evaluation again.

Entering Commands

You must enter the greater than sign (>) when issuing Visual Studio commands in the Immediate window. Use the UP ARROW and DOWN ARROW keys to scroll through previously issued commands.

Task

Solution

Example

Evaluate an expression.

Preface the expression with a question mark (?).

? a+b

Temporarily enter Command mode while in Immediate mode (to execute a single command).

Enter the command, prefacing it with a greater than sign (>).

>alias

Switch to the Command window.

Enter cmd into the window, prefacing it with a greater than sign (>).

>cmd

Switch back to the Immediate window.

Enter immed into the window without the greater than sign (>).

immed

Mark Mode

When you click on any previous line in the Immediate window, you shift automatically into Mark mode. This allows you to select, edit, and copy the text of previous commands as you would in any text editor, and paste them into the current line.

The Equals (=) Sign

The window used to enter the EvaluateStatement command determines whether an equals sign (=) is interpreted as a comparison operator or as an assignment operator.

In the Immediate window, an equals sign (=) is interpreted as an assignment operator. So, for example, the command

>Debug.EvaluateStatement(varA=varB)

will assign to variable varA the value of variable varB.

In the Command window, by contrast, an equals sign (=) is interpreted as a comparison operator. You cannot use assignment operations in the Command window. So, for example, if the values of variables varA and varB are different, then the command

>Debug.EvaluateStatement(varA=varB)

will return a value of False.

First-Chance Exception Notifications

In some settings configurations, first-chance exception notifications are displayed in the Immediate window.

To toggle first-chance exception notifications in the Immediate window

  1. On the View menu, click Other Windows, and click Output.

  2. Right-click on the text area of the Output window, and select or deselect Exception Messages.

See Also

Tasks

Walkthrough: Debugging at Design Time

Reference

Command Window

Predefined Visual Studio Command Aliases

Regular Expressions (Visual Studio)

Concepts

Breaking During Function Evaluation in the Visual Studio Debugger

Other Resources

Debugging in Visual Studio

Debugger Roadmap