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Compiler Error CS1931

Visual Studio 2008

The range variable 'variable' conflicts with a previous declaration of 'variable'.

The declaration of a range variable, just like every other declaration, must have an identifier which is unique within the variable's declaration space.

To correct this error

  • Give the range variable a unique name.

The following code generates CS1931 because the identifier x is used both as a local variable in Main and as the range variable in the query expression:

// cs1931.cs
class Test
        static void Main()
            int x = 1;
            var y = from x in Enumerable.Range(1, 100) // CS1931
                    select x;