C# Error CS0844 – Cannot use local variable ‘{0}’ before it is declared. The declaration of the local variable hides the field ‘{1}’.

C# Error

CS0844 – Cannot use local variable ‘{0}’ before it is declared. The declaration of the local variable hides the field ‘{1}’.

Reason for the Error & Solution

Cannot use local variable ‘name’ before it is declared. The declaration of the local variable hides the field ‘name’.

An identifier can have only one meaning in a given block. Local variables that have the same name as class fields can hide the field by introducing a second meaning for the identifier. Therefore the compiler generates an error when you refer to a class field in a method, and then declare a local variable by the same name.

To correct this error

• Use this.num to refer to the class field.

• Give the local variable a different name from the class field.

Example

The following code generates CS0844:

class Test  
    {  
        int num;  
        public void TestMethod()  
        {  
            num = 5; // CS0844  
            int num = 6;
        }  
        public static int Main()  
        {  
            return 1;  
        }  
    }  

Correct the error by using this.num to refer to the class field

class Test  
    {  
        int num;  
        public void TestMethod()  
        {  
            this.num = 5; // Error fixed.
            int num = 6;
        }  
        public static int Main()  
        {  
            return 1;  
        }  
    }  

Correct the error by giving the local variable a different name from the class field

class Test  
    {  
        int num;  
        public void TestMethod()  
        {  
            num = 5; // Error fixed.
            int num2 = 6;
        }  
        public static int Main()  
        {  
            return 1;  
        }  
    }