Why can't I have "public static const string S = "stuff"; in my Class?

Viewed 158711

When trying to compile my class I get an error:

The constant 'NamespaceName.ClassName.CONST_NAME' cannot be marked static.

at the line:

public static const string CONST_NAME = "blah";

I could do this all of the time in Java. What am I doing wrong? And why doesn't it let me do this?

6 Answers

From the C# language specification (PDF page 287 - or 300th page of the PDF):

Even though constants are considered static members, a constant declaration neither requires nor allows a static modifier.

A const member is considered static by the compiler, as well as implying constant value semantics, which means references to the constant might be compiled into the using code as the value of the constant member, instead of a reference to the member.

In other words, a const member containing the value 10, might get compiled into code that uses it as the number 10, instead of a reference to the const member.

This is different from a static readonly field, which will always be compiled as a reference to the field.

Note, this is pre-JIT. When the JIT'ter comes into play, it might compile both these into the target code as values.

Related