Keyword

# While...Wend

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## Description

Repeatedly executes a series of statements while a specified condition is `True</api/language/true>`.

## Usage

``` xojo
While Condition
  [ Statements ]
  [ Continue [ While ] ]
  [ Exit [ While ] ]
  [ Statements ]
Wend 
```

| Part                                     | Description                                                                                                                                                                    |
|------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| While                                    | Begins the loop. *Condition* is evaluated to determine if the loop should exit.                                                                                                |
| Condition                                | Any valid `Boolean</api/data_types/boolean>` expression. When this expression evaluates to `True</api/language/true>`, the loop will continue to execute.                      |
| Statements                               | Statements to be executed repeatedly until *Condition* evaluates to `False</api/language/false>`.                                                                              |
| `Continue</api/language/loops/continue>` | If a `Continue</api/language/loops/continue>` statement is present, execution will skip over the remaining statements in the loop and resume with a new iteration of the loop. |
| `Exit</api/language/loops/exit>`         | If an `Exit</api/language/loops/exit>` statement is present, execution of the loop is terminated and resumes with the next line following the loop.                            |
| Wend                                     | Ends the loop.                                                                                                                                                                 |

## Notes

If *Condition* is `True</api/language/true>`, all statements are executed until the Wend statement is reached. If *Condition* is still `True</api/language/true>`, the process is repeated. If *Condition* is `False</api/language/false>`, then execution continues with the statement following the Wend statement.

While...Wend statements can be nested to any level. Each Wend statement goes with the previous While statement. It is permissible to place `Var</api/language/var>` statements inside loops, including While loops.

If a variable is declared inside a While statement, it goes out of scope after the last iteration of the loop. For example,

``` xojo
Var i As Integer
While I < 100
  Var a As Integer
  a = i + 1
Wend
MessageBox(a.ToString) ' 'a' is out of scope
```

This loop makes sense with the variable "a" declared outside the loop.

When a loop runs, it takes over the interface, preventing the user from interacting with menus and controls. If the loop is very lengthy, you can move the code for the loop to a separate `Thread</api/language/threading/thread>`, allowing it to execute in the background.

## Sample code

This example uses the <span class="title-ref">While...Wend</span> statement to increment a variable.

``` xojo
Var x As Integer
While x < 100
  x = x + 1
Wend
```

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Using Exit:

``` xojo
Const kAttempts = 10
Var attempt As Integer = 1
Var output As String

While attempt <= kAttempts
  Var randomValue As Integer = System.Random.InRange(1, 10)
  If randomValue > 5 Then
    output = "Found a random value above 5 after " + attempt.ToString + " iterations."
    Exit
  End If
  attempt = attempt + 1
Wend

If attempt > kAttempts Then
  output = "Found NO random value above 5 after " + kAttempts.ToString + " iterations."
End If
```

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Using Continue:

``` xojo
Const kAttempts = 100
Var matchCount As Integer
Var attempt As Integer

While attempt < kAttempts
  attempt = attempt + 1
  Var randomValue As Integer = System.Random.InRange(1, 10)
  If randomValue <= 5 Then
    Continue
  End If
  matchCount = matchCount + 1
Wend

Var output As String
output = "Found " + matchCount.ToString + " random values above 5 within " + kAttempts.ToString + " iterations."
```

## Compatibility

|                       |     |
|-----------------------|-----|
| **Project Types**     | All |
| **Operating Systems** | All |

<div class="seealso">

`Continue</api/language/loops/continue>`, `Do...Loop</api/language/loops/do...loop>`, `Exit</api/language/loops/exit>`, `For...Next</api/language/loops/for...next>` statements; `DesktopApplication</api/user_interface/desktop/desktopapplication>`, `Thread</api/language/threading/thread>` classes.

</div>