C# 如何检查枚举是否包含数字？
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How to check If a Enum contain a number?
提问by Hyman Zhang
I have a Enum like this:
我有一个这样的枚举：
public enum PromotionTypes
{
Unspecified = 0,
InternalEvent = 1,
ExternalEvent = 2,
GeneralMailing = 3,
VisitBased = 4,
PlayerIntroduction = 5,
Hospitality = 6
}
I want to check if this Enum contain a number I give. For example: When I give 4, Enum contain that, So I want to return True, If I give 7, There isn't 7 in this Enum, So it returns False. I tried Enum.IsDefine but it only check the String value. How can I do that?
我想检查这个 Enum 是否包含我给出的数字。例如：当我给出 4 时，Enum 包含那个，所以我想返回 True，如果我给出 7，这个 Enum 中没有 7，所以它返回 False。我试过 Enum.IsDefine 但它只检查字符串值。我怎样才能做到这一点？
采纳答案by John Woo
The IsDefinedmethod requires two parameters. The first parameter is the type of the enumeration to be checked. This type is usually obtained using a typeof expression. The second parameter is defined as a basic object. It is used to specify either the integer value or a string containing the name of the constant to find. The return value is a Boolean that is true if the value exists and false if it does not.
该IsDefined方法需要两个参数。第一个参数是要检查的枚举类型。这种类型通常使用 typeof 表达式获得。的第二个参数被定义为基本对象。它用于指定整数值或包含要查找的常量名称的字符串。返回值是一个布尔值，如果该值存在则为真，否则为假。
enum Status
{
OK = 0,
Warning = 64,
Error = 256
}
static void Main(string[] args)
{
bool exists;
// Testing for Integer Values
exists = Enum.IsDefined(typeof(Status), 0); // exists = true
exists = Enum.IsDefined(typeof(Status), 1); // exists = false
// Testing for Constant Names
exists = Enum.IsDefined(typeof(Status), "OK"); // exists = true
exists = Enum.IsDefined(typeof(Status), "NotOK"); // exists = false
}
回答by horgh
Try this:
尝试这个：
IEnumerable<int> values = Enum.GetValues(typeof(PromotionTypes))
.OfType<PromotionTypes>()
.Select(s => (int)s);
if(values.Contains(yournumber))
{
//...
}
回答by Cheng Chen
You should use Enum.IsDefined.
你应该使用Enum.IsDefined.
I tried Enum.IsDefine but it only check the String value.
我试过 Enum.IsDefine 但它只检查字符串值。
I'm 100% sure it will check both string value and int(the underlying) value, at least on my machine.
我 100% 肯定它会检查字符串值和 int（底层）值，至少在我的机器上。
回答by Hulzi
Maybe you want to check and use the enum of the string value:
也许您想检查并使用字符串值的枚举：
string strType;
if(Enum.TryParse(strType, out MyEnum myEnum))
{
// use myEnum
}
