Static (Visual Basic)Static (Visual Basic)

指定一個或多個宣告的區域變數要繼續存在,並在終止宣告它們的程式之後保留其最新值。Specifies that one or more declared local variables are to continue to exist and retain their latest values after termination of the procedure in which they are declared.

備註Remarks

一般來說,程式停止時,程式中的區域變數就會停止存在。Normally, a local variable in a procedure ceases to exist as soon as the procedure stops. 靜態變數會繼續存在,並保留其最新的值。A static variable continues to exist and retains its most recent value. 下一次您的程式碼呼叫程式時,變數不會重新初始化,而且仍然會保留您指派給它的最新值。The next time your code calls the procedure, the variable is not reinitialized, and it still holds the latest value that you assigned to it. 靜態變數會繼續存在於其定義所在之類別或模組的存留期間。A static variable continues to exist for the lifetime of the class or module that it is defined in.

規則Rules

  • 宣告內容。Declaration Context. 您只能在本機變數上使用 StaticYou can use Static only on local variables. 這表示 Static 變數的宣告內容必須是程式或程式中的區塊,而且不能是原始程式檔、命名空間、類別、結構或模組。This means the declaration context for a Static variable must be a procedure or a block in a procedure, and it cannot be a source file, namespace, class, structure, or module.

    您不能在結構程式中使用 StaticYou cannot use Static inside a structure procedure.

  • 無法推斷 Static 本機變數的資料類型。The data types of Static local variables cannot be inferred. 如需詳細資訊,請參閱區欄位型別推斷For more information, see Local Type Inference.

  • 合併的修飾詞。Combined Modifiers. 您不能在相同的宣告中同時指定 StaticReadOnlyShadowsSharedYou cannot specify Static together with ReadOnly, Shadows, or Shared in the same declaration.

行為Behavior

當您在 Shared 程式中宣告靜態變數時,整個應用程式只能有一個靜態變數複本。When you declare a static variable in a Shared procedure, only one copy of the static variable is available for the whole application. 您可以使用類別名稱來呼叫 Shared 程式,而不是指向類別實例的變數。You call a Shared procedure by using the class name, not a variable that points to an instance of the class.

當您在不 Shared的程式中宣告靜態變數時,類別的每個實例只能有一個變數複本。When you declare a static variable in a procedure that isn't Shared, only one copy of the variable is available for each instance of the class. 您可以使用指向類別之特定實例的變數來呼叫非共用程式。You call a non-shared procedure by using a variable that points to a specific instance of the class.

範例Example

下列範例示範 Static 的用法。The following example demonstrates the use of Static.

Function updateSales(ByVal thisSale As Decimal) As Decimal
    Static totalSales As Decimal = 0
    totalSales += thisSale
    Return totalSales
End Function

Static 變數 totalSales 只會初始化為0一次。The Static variable totalSales is initialized to 0 only one time. 每次您輸入 updateSales時,totalSales 仍會有您為它計算的最新值。Each time that you enter updateSales, totalSales still has the most recent value that you calculated for it.

Static 修飾詞可以在此內容中使用:The Static modifier can be used in this context:

Dim 陳述式Dim Statement

請參閱See also