是否允许有一个以数字开头的枚举成员名称？ [英] Is is allowed to have an Enum member name that start with a number?

问题描述

我正在尝试设置一个枚举来保持钣金尺寸（厚度）。我认为如果我可以写：

 使用System.ComponentModel，这将是最直观的; 
 public enum Gauge 
 {
 [描述（24 Gauge）] 
 24Ga = 239，
 [描述（20 Gauge）] 
 20Ga = 359，
 [描述（18 Gauge）] 
 18Ga = 478，
 [描述（16 Gauge）] 
 16Ga = 598，
 [描述（14 Gauge）] 
 14Ga = 747 
} 
  

但是这被Visual Studio拒绝。

相反，这是可以的：

 使用System.ComponentModel; 
 public enum Gauge 
 {
 [描述（24 Gauge）] 
 G24 = 239，
 [描述（20 Gauge）] 
 G20 = 359，
 [描述（18 Gauge）] 
 G18 = 478，
 [描述（16 Gauge）] 
 G16 = 598，
 [描述（14 Gauge）] 
 G14 = 747 
} 
  

这使得看起来很明显的是，您不能使用数字字符启动枚举成员名称，即使通常允许使用变量名称。

我的问题是：这个限制在哪里？ Enum Class文档似乎没有提到它。

解决方案

是否允许有一个以枚数开头的枚举成员名一个数字？

不，语言语法不允许。

请参见 2.4.2标识符

  identifier-start-character：
 letter-character 
 _（下划线字符U + 005F）
  

I am trying to set up an enum to hold sheet metal gauges (thicknesses). I thought it would be most intuitive if I could write:

using System.ComponentModel;
public enum Gauge
{
    [Description("24 Gauge")]
    24Ga = 239,
    [Description("20 Gauge")]
    20Ga = 359,
    [Description("18 Gauge")]
    18Ga = 478,
    [Description("16 Gauge")]
    16Ga = 598,
    [Description("14 Gauge")]
    14Ga = 747
}

but this is rejected by Visual Studio.

Instead this is OK:

using System.ComponentModel;
public enum Gauge
{
    [Description("24 Gauge")]
    G24 = 239,
    [Description("20 Gauge")]
    G20 = 359,
    [Description("18 Gauge")]
    G18 = 478,
    [Description("16 Gauge")]
    G16 = 598,
    [Description("14 Gauge")]
    G14 = 747
}

This makes it seem pretty obvious that you are not allowed to start a Enum member name off with a numeric character, even though that is usually allowed for variable names.

My question is: Where is this restriction specified? The Enum Class documentation does not seem to mention it.

解决方案

Is is allowed to have an Enum member name that start with a number?

No, the language syntax does not allow it.

See 2.4.2 Identifiers

identifier-start-character:
    letter-character
    _ (the underscore character U+005F) 

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