C# Guid 類型/結構介紹

在 C# 中產生 Guid ，並以不同的格式顯示：

    
        Guid guid = Guid.NewGuid();
        Console.WriteLine("guid: " + guid); // f3079291-9008-423f-ae53-07740dc1ac37
        Console.WriteLine("guid: " + guid.ToString("D")); // f3079291-9008-423f-ae53-07740dc1ac37
        Console.WriteLine("guid: " + guid.ToString("N")); // f30792919008423fae5307740dc1ac37
        Console.WriteLine("guid: " + guid.ToString("B")); // {f3079291-9008-423f-ae53-07740dc1ac37}
        Console.WriteLine("guid: " + guid.ToString("P")); // (f3079291-9008-423f-ae53-07740dc1ac37)
        Console.WriteLine("guid: " + guid.ToString("X")); // {0xf3079291,0x9008,0x423f,{0xae,0x53,0x07,0x74,0x0d,0xc1,0xac,0x37}}
    

將字串的 GUID 轉換為 Guid 型態：

    
string guidString = "B7EB7C1AB80F4BCEB89189DB6A7383B8";
Guid guidFromString = Guid.Parse(guidString);
Console.WriteLine(guidFromString); // b7eb7c1a-b80f-4bce-b891-89db6a7383b8
    

假設字串格式錯誤，無法轉換為 Guid 則會拋出以下例外：

    
Unhandled exception. System.FormatException: Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).
   at System.Guid.GuidResult.SetFailure(ParseFailure failureKind)
   at System.Guid.TryParseExactN(ReadOnlySpan`1 guidString, GuidResult& result)
   at System.Guid.TryParseGuid(ReadOnlySpan`1 guidString, GuidResult& result)
   at System.Guid.Parse(ReadOnlySpan`1 input)
   at System.Guid.Parse(String input)
   at ConsoleAppGuidTest0930.Program.Main(String[] args) in C:\Users\ruyut\Test\Program.cs:line 28

    

不想處理例外也可以使用 Guid.TryParse 方法，如果轉換失敗則會回傳 false ，而不是拋出例外

    
string guidString = "B7EB7C1AB80F4BCEB89189DB6A7383B8";
if (Guid.TryParse(guidString, out Guid guid))
{
    Console.WriteLine(guid); // b7eb7c1a-b80f-4bce-b891-89db6a7383b8
}
else
{
    Console.WriteLine("Invalid GUID");
}
    

延伸閱讀： UUID/GUID 介紹和使用 C# 產生 GUID 示範

參考資料：
Microsoft.Learn - Guid Struct