变量已分配但从未使用其值 (C#)

Question

In Visual Studio I used the following code:

 private bool answer = true;
    Private Buttonclick()
   {
      if()
       {
        answer =false
        }
   }

Compiler gives me a warning that says "answer is assigned but its value is never used". How do I fix this?

Answer 1

It means you have given answer a value, but not referenced it elsewhere. Meaning you are not using answer elsewhere in your program.

You fix it by referencing answer from another part of your program.

Answer 2

The reason the warning pops up is not because the variable is never assigned, but because it is in fact never used for any sort of comparison in the rest of the code.

Please go through this reference: http://weblog.west-wind.com/posts/2009/Feb/28/Variable-is-assigned-but-its-Value-is-never-used-Warning

Answer 3

If you want to disable warnings, the error list contains a button that can stop them being shown in the list.

Additionally, a warning is just a warning. They won't stop your program from compiling, or even running. They may, however, declare in advance runtime errors and the like, so don't ignore them completely.

Answer 4

In addition to the answers above, for more deep understanding of the this warning:

This warning will not always pop-up (if you not use assigned variable). Assigning a non-constant expression or method result will NOT generate the warning. It is done intentionally, since such an unassigned variables can be used in debugging.

For example:

 var answer = SomeObject.SomePropery; //will not generate CS0219

There are excellent explanation in Microsoft.Docs: https://docs.microsoft.com/en-us/dotnet/csharp/misc/cs0219