C＃中的内联IF语句

Question

How will I write an Inline IF Statement in my C# Service class when setting my enum value according to what the database returned?

For example: When the database value returned is 1 then set the enum value to VariablePeriods, when 2 then FixedPeriods.

Hope you can help.

Answer 1

The literal answer is:

return (value == 1 ? Periods.VariablePeriods : Periods.FixedPeriods);

Note that the inline if statement, just like an if statement, only checks for true or false. If (value == 1) evaluates to false, it might not necessarily mean that value == 2. Therefore it would be safer like this:

return (value == 1
    ? Periods.VariablePeriods
    : (value == 2
        ? Periods.FixedPeriods
        : Periods.Unknown));

If you add more values an inline if will become unreadable and a switch would be preferred:

switch (value)
{
case 1:
    return Periods.VariablePeriods;
case 2:
    return Periods.FixedPeriods;
}

The good thing about enums is that they have a value, so you can use the values for the mapping, as user854301 suggested. This way you can prevent unnecessary branches thus making the code more readable and extensible.

Answer 2

You may define your enum like so and use cast where needed

public enum MyEnum
{
    VariablePeriods = 1,
    FixedPeriods = 2
}

Usage

public class Entity
{
    public MyEnum Property { get; set; }
}

var returnedFromDB = 1;
var entity = new Entity();
entity.Property = (MyEnum)returnedFromDB;

Answer 3

You can do inline ifs with

return y == 20 ? 1 : 2;

which will give you 1 if true and 2 if false.

Answer 4

This is what you need : ternary operator, please take a look at this

http://msdn.microsoft.com/en-us/library/ty67wk28%28v=vs.80%29.aspx

http://www.dotnetperls.com/ternary

Answer 5

Enum to int: (int)Enum.FixedPeriods

Int to Enum: (Enum)myInt