将变量与多个值进行比较

Question

在我的代码中,我经常需要将变量与几个值进行比较:

if ( type == BillType.Bill || type == BillType.Payment || type == BillType.Receipt )
{
  // Do stuff
}

我一直在想我能做到:

if ( type in ( BillType.Bill, BillType.Payment, BillType.Receipt ) )
{
   // Do stuff
}

但当然那是允许这种情况的SQL.

C#中有更整洁的方式吗？

Answer 1

你可以用.Contains这样做:

if(new[]{BillType.Receipt,BillType.Bill,BillType.Payment}.Contains(type)){}

或者,使用更易读的语法创建自己的扩展方法

public static class MyExtensions
{
    public static bool IsIn<T>(this T @this, params T[] possibles)
    {
        return possibles.Contains(@this);
    }
}

然后叫它:

if(type.IsIn(BillType.Receipt,BillType.Bill,BillType.Payment)){}

Answer 2

还有switch语句

switch(type) {
    case BillType.Bill:
    case BillType.Payment:
    case BillType.Receipt:
        // Do stuff
        break;
}

Answer 3

假设type是枚举,您可以使用FlagsAttribute:

[Flags]
enum BillType
{
    None = 0,
    Bill = 2,
    Payment = 4,
    Receipt = 8
}

if ((type & (BillType.Bill | BillType.Payment | BillType.Receipt)) != 0)
{
    //do stuff
}