在多个条件下测试C＃枚举标志

Question

I have a test program. I want to use an enum with flags to test multiple conditions but i get the wrong result.

This is my enum :

[Flags]
enum CoverOptionTypes
{
    MainLife = 0x0001,
    PolicyPayerMainLife = 0x0002,
    Spouse = 0x0004,
    Child = 0x0008,
    AdditionalChildren = 0xF
}

When i create the enum and assign values, i dont seem to get the expected values.

If i do this

var option = CoverOptionTypes.MainLife;

and test with the following :

if (option.HasFlag(CoverOptionTypes.MainLife)
{
    Console.WriteLine("Main + PP Screen + Parents + Ext Family");
}

I get the correct output. When i try multiple scenarios as follows :

var option = CoverOptionTypes.MainLife;
option |= CoverOptionTypes.PolicyPayerMainLife;
option |= CoverOptionTypes.Child;
option |= CoverOptionTypes.AdditionalChildren;


if (option.HasFlag(CoverOptionTypes.MainLife) && (
    option.HasFlag(CoverOptionTypes.PolicyPayerMainLife) &&
    !option.HasFlag(CoverOptionTypes.Spouse) &&
    !option.HasFlag(CoverOptionTypes.Child) &&
    !option.HasFlag(CoverOptionTypes.AdditionalChildren)))
{
    Console.WriteLine("Main + PP Screen + Parents + Ext Family");
}
else if (option.HasFlag(CoverOptionTypes.MainLife) &&(
        option.HasFlag(CoverOptionTypes.PolicyPayerMainLife) &&
        option.HasFlag(CoverOptionTypes.Spouse) &&
        !option.HasFlag(CoverOptionTypes.Child) &&
    !option.HasFlag(CoverOptionTypes.AdditionalChildren)))
{
    Console.WriteLine("Main + Spouse + PP Screen + Parents + Ext Family");
}
else if (option.HasFlag(CoverOptionTypes.MainLife) && (
         option.HasFlag(CoverOptionTypes.PolicyPayerMainLife) &&
         option.HasFlag(CoverOptionTypes.Spouse) && 
         option.HasFlag(CoverOptionTypes.Child) &&
         !option.HasFlag(CoverOptionTypes.AdditionalChildren)))
{
    Console.WriteLine("Main + Spouse + Child + PP Screen + Parents + Ext Family");
}
else if (option.HasFlag(CoverOptionTypes.MainLife) && (
         option.HasFlag(CoverOptionTypes.PolicyPayerMainLife) &&
         option.HasFlag(CoverOptionTypes.Spouse) &&
         option.HasFlag(CoverOptionTypes.Child) &&
         option.HasFlag(CoverOptionTypes.AdditionalChildren)))
{
    Console.WriteLine("Main + Spouse + Child + Additional Children + PP Screen + Parents + Ext Family");
}
else if (option.HasFlag(CoverOptionTypes.MainLife) && (
         option.HasFlag(CoverOptionTypes.PolicyPayerMainLife) &&
         !option.HasFlag(CoverOptionTypes.Spouse) &&
         option.HasFlag(CoverOptionTypes.Child) &&
         !option.HasFlag(CoverOptionTypes.AdditionalChildren)))
{
    Console.WriteLine("Main  + Child + PP Screen + Parents + Ext Family");
}
else if (option.HasFlag(CoverOptionTypes.MainLife) && (
         option.HasFlag(CoverOptionTypes.PolicyPayerMainLife) &&
         !option.HasFlag(CoverOptionTypes.Spouse) &&
         option.HasFlag(CoverOptionTypes.Child) &&
         option.HasFlag(CoverOptionTypes.AdditionalChildren)))
{
    Console.WriteLine("Main  + Child + Additional Chidren + PP Screen + Parents + Ext Family");
}

I get this output

Main + Spouse + Child + Additional Children + PP Screen + Parents + Ext Family

The output is wrong as i do not have the Spouse flag turned on. When i debug, i can see the flags set but the if decision goes into the wrong if statement.

Answer 1

Pretty sure this is because of the integer values you chose for your enum.

Consider the following:

HasFlag formula is (int)EnumValue & (int)TargetValue = (int)TargetValue (source: https://msdn.microsoft.com/en-us/library/system.enum.hasflag.aspx?f=255&MSPPError=-2147217396 )

Using this, we can see that

0xF & 0x0004 returns 0x0004

Which basically means that when AdditionalChildren is set, Spouse is also set.

Also, your MainLife and PolicyPayerMainLife have the same values.