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# Function Statement

A function is a block of code which runs when it is called. A function is usually called in an expression.

You can pass data, known as parameters or arguments, into a function. You may pass a parameter by value or by reference. When by reference, modifications applied to the parameter in the function will be sent back to the calling code.

A function usually returns data as a result.

### Syntax:

      [Private | Public] Function Name[char] (argument1 [As Type][, argument2[char][,...]]) [As typename]
              statements
          [Exit Function]
              statements
      End Function

### Parameters:

scope: Function default scope is Public. A Private scope denotes a module internal routine, not intended to be used from other modules.

name: Name of the subroutine to contain the value returned by the function.

arguments: Parameters to be passed to the subroutine.

##### argument fragment

          {[Optional [ByRef|ByVal]]|ParamArray} argument {{As typename|char}[ = expression]|[()]As Variant}

##### Parameters

Optional: The argument is not mandatory.

ByRef: The argument is passed by reference. ByRef is the default.

ByVal: The argument is passed by value. Its value can be modified by the called routine.

char: Type declaration character.

typename: Primitive data type name. Library or module defined types can also be specified.

= expression: Specify a default value for the argument, matching its declared type. Optional is necessary for each argument specifying a default value.

ParamArray: Use ParamArray when the number of parameters is undetermined. A typical scenario is that of a Calc user-defined function. Using ParamArray should be limited to the last argument of a routine.

UsingParamArray or = expression require Option Compatible to be placed before the executable program code in a module.

When using Option VBASupport 1, Optional arguments with no default value (= expression) are initialized according to their data type, except if Variant.

##### typename fragment

          {Boolean|Byte|Currency|Date|Double|Integer|Long|Object|Single|String|Variant}

##### char fragment

          { % | & | ! | # | $ | @ }

## Examples:

    Sub ExampleExit
    Dim sReturn As String
    Dim sListArray(10) As String
    Dim siStep As Single
        For siStep = 0 to 10  REM 配列にテスト用データを代入
            sListArray(siStep) = chr$(siStep + 65)
            MsgBox sListArray(siStep)
        Next siStep
        sReturn = LinSearch(sListArray(), "B")
        Print sReturn
    End Sub

    Function LinSearch( sList(), sItem As String ) As Integer
    Dim iCount As Integer
    REM LinSearch はテキスト配列 sList( ) 内に指定文字列を検索
    REM 戻り値は、該当するインデックス値ないしゼロ (Null)
        For iCount=1 To Ubound( sList() )
            If sList( iCount ) = sItem Then
                Exit for REM 検索で sItem がヒット
            End If
        Next iCount
        If iCount = Ubound( sList() ) Then iCount = 0
        LinSearch = iCount
    End Function

関連項目

Subroutines basics

Using Procedures, Functions and Properties

Sub Statement

Property Statement

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