我为什么要投枚举在C＃中为int？ [英] Why do I have to cast enums to int in C#?

问题描述

这是我的代码：

internal enum WindowsMessagesFlags {
    WM_EXITSIZEMOVE      = 0x00000232,
    WM_DISPLAYCHANGE     = 0x0000007e,
    WM_MOVING            = 0x00000216,
}

protected override void WndProc(ref Message m) {
    switch(m.Msg) {
    	case (int)WindowsMessagesFlags.WM_DISPLAYCHANGE:
    		FixWindowSnapping();
    		break;
    	case (int)WindowsMessagesFlags.WM_EXITSIZEMOVE:
    		SaveWindowProperties();
    		break;
    	case (int)WindowsMessagesFlags.WM_MOVING:
    		KeepProperLocation(ref m);
    		break;
    }
}

反正是有防止铸件？

Is there anyway to prevent the casting?

推荐答案

排序 - 投m.Msg来代替：

Sort of - cast m.Msg instead:

protected override void WndProc(ref Message m) {
    switch((WindowsMessagesFlags) m.Msg) {
        case WindowsMessagesFlags.WM_DISPLAYCHANGE:
                FixWindowSnapping();
                break;
        case WindowsMessagesFlags.WM_EXITSIZEMOVE:
                SaveWindowProperties();
                break;
        case WindowsMessagesFlags.WM_MOVING:
                KeepProperLocation(ref m);
                break;
    }
}

您需要演员在所有的原因是因为在C＃枚举不仅仅是数字 - 他们是与类型相关联的数字。这可以防止你做（不含铸造）：

The reason you need the cast at all is because in C# enums aren't just numbers - they're numbers associated with the type. This prevents you from doing (without casting):

HttpStatusCode status = someWindowsMessageFlag;

这显然是一件好事:)当你需要，但是，你可以随时去通过底层的类型（INT在这种情况下）。

This is clearly a good thing :) When you need to, however, you can always go "via" the underlying type (int in this case).

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