Enum.Format(Type, Object, String) 方法

定義

根據指定的格式,將指定列舉類型的指定值轉換為相等的字串表示。Converts the specified value of a specified enumerated type to its equivalent string representation according to the specified format.

public:
 static System::String ^ Format(Type ^ enumType, System::Object ^ value, System::String ^ format);
public static string Format (Type enumType, object value, string format);
[System.Runtime.InteropServices.ComVisible(true)]
public static string Format (Type enumType, object value, string format);
static member Format : Type * obj * string -> string
[<System.Runtime.InteropServices.ComVisible(true)>]
static member Format : Type * obj * string -> string
Public Shared Function Format (enumType As Type, value As Object, format As String) As String

參數

enumType
Type

要轉換的數值列舉類型。The enumeration type of the value to convert.

value
Object

要進行轉換的值。The value to convert.

format
String

要使用的輸出格式。The output format to use.

傳回

String

value 的字串表示。A string representation of value.

屬性

例外狀況

enumTypevalueformat 參數是 nullThe enumType, value, or format parameter is null.

enumType 參數不是 Enum 類型。The enumType parameter is not an Enum type.

-或--or- value 來自與 enumType 類型不同的列舉。The value is from an enumeration that differs in type from enumType.

-或--or- 類型 value 不是 enumType 的基礎類型。The type of value is not an underlying type of enumType.

format 參數包含無效的值。The format parameter contains an invalid value.

format 等於 "X",但列舉類型未知。format equals "X", but the enumeration type is unknown.

範例

下列範例說明如何 Format 在的內容中使用 EnumThe following example illustrates the use of Format in the context of Enum.

using namespace System;
public enum class Colors
{
   Red, Green, Blue, Yellow
};

int main()
{
   Colors myColor = Colors::Blue;
   Console::WriteLine(  "My favorite color is {0}.", myColor );
   Console::WriteLine(  "The value of my favorite color is {0}.", Enum::Format( Colors::typeid, myColor,  "d" ) );
   Console::WriteLine(  "The hex value of my favorite color is {0}.", Enum::Format( Colors::typeid, myColor,  "x" ) );
}
// The example displays the folowing output:
//    My favorite color is Blue.
//    The value of my favorite color is 2.
//    The hex value of my favorite color is 00000002.
using System;

enum Colors { Red, Green, Blue, Yellow };

public class FormatTest {
    public static void Main() {
        Colors myColor = Colors.Blue;

        Console.WriteLine("My favorite color is {0}.", myColor);
        Console.WriteLine("The value of my favorite color is {0}.", Enum.Format(typeof(Colors), myColor, "d"));
        Console.WriteLine("The hex value of my favorite color is {0}.", Enum.Format(typeof(Colors), myColor, "x"));
    }
}
// The example displays the following output:
//    My favorite color is Blue.
//    The value of my favorite color is 2.
//    The hex value of my favorite color is 00000002.
 Enum Colors
     Red
     Green
     Blue
     Yellow    
 End Enum
    
Public Class FormatTest
    Public Shared Sub Main()
        Dim myColor As Colors = Colors.Blue
        
        Console.WriteLine("My favorite color is {0}.", myColor)
        Console.WriteLine("The value of my favorite color is {0}.", [Enum].Format(GetType(Colors), myColor, "d"))
        Console.WriteLine("The hex value of my favorite color is {0}.", [Enum].Format(GetType(Colors), myColor, "x"))
    End Sub 
End Class 
' The example displays the following output:
'    My favorite color is Blue.
'    The value of my favorite color is 2.
'    The hex value of my favorite color is 00000002.

備註

下表顯示參數的有效值 formatThe following table shows the valid values for the format parameter.

格式Format 描述Description
"G" 或 "g""G" or "g" 如果 value 等於命名的列舉常數,則會傳回該常數的名稱; 否則會傳回 decimal 對等的 valueIf value is equal to a named enumerated constant, the name of that constant is returned; otherwise, the decimal equivalent of value is returned.

例如,假設唯一列舉的常數命名為紅色,其值為1。For example, suppose the only enumerated constant is named Red, and its value is 1. 如果 value 指定為1,此格式會傳回 "Red"。If value is specified as 1, this format returns "Red". 但是,如果 value 指定為2,此格式會傳回 "2"。However, if value is specified as 2, this format returns "2".

-或--or-

如果 FlagsAttribute 自訂屬性套用至列舉, value 則會被視為位欄位,其中包含一或多個位組成的一個或多個旗標。If the FlagsAttribute custom attribute is applied to the enumeration, value is treated as a bit field that contains one or more flags that consist of one or more bits.

如果 value 等於命名列舉常數的組合,則會傳回這些常數名稱的分隔清單。If value is equal to a combination of named enumerated constants, a delimiter-separated list of the names of those constants is returned. value 會搜尋旗標,從具有最大值的旗標到最小值。value is searched for flags, going from the flag with the largest value to the smallest value. 針對每個對應到中位欄位的旗標 value ,常數的名稱會串連成以分隔符號分隔的清單。For each flag that corresponds to a bit field in value, the name of the constant is concatenated to the delimiter-separated list. 接著,該旗標的值會排除在進一步的考慮範圍內,而搜尋會繼續進行下一個旗標。The value of that flag is then excluded from further consideration, and the search continues for the next flag.

如果不 value 等於命名列舉常數的組合,則會傳回的十進位對等用法 valueIf value is not equal to a combination of named enumerated constants, the decimal equivalent of value is returned.
"X" 或 "x""X" or "x" value以十六進位格式表示,但不含前置的 "0x"。Represents value in hexadecimal format without a leading "0x".
"D" 或 "d""D" or "d" value以十進位形式表示。Represents value in decimal form.
"F" 或 "f""F" or "f" 行為與 "G" 或 "g" 相同,不同之處在于宣告中 FlagsAttribute 不需要有 EnumBehaves identically to "G" or "g", except that the FlagsAttribute is not required to be present on the Enum declaration.

適用於

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