#319 – You Initialize a Constant Using an Expression

You initialize a constant in C# using either a literal or an expression that resolves to the correct type.

    public class Dog
    {
        const string Demeanor = "friendly";
        const int NumberOfLegs = 4;
        const double OneThird = 1.0 / 3.0;

You can also use the value of another constant in a constant expression.

        const int NumberOfLegs = 4;
        const int NumberOfEyes = 2;
        const int EyeAndLegCount = NumberOfLegs + NumberOfEyes;

The constant expression must be able to be resolved at compile time, so you can’t use something that is not a constant.  This includes variables and also includes the results of method calls.

        static int NumLegs = 4;   // Not a constant

        // Error: The expression being assigned to 'ConsoleApplication2.Dog.LegsPlusOne' must be constant
        const int LegsPlusOne = NumLegs + 1;
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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #319 – You Initialize a Constant Using an Expression

  1. Pingback: #586 – Default Values for Optional Parameters Must Be Constants « 2,000 Things You Should Know About C#

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