Compiler Error CS1061

 

Updated: July 20, 2015

For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

'type' does not contain a definition for 'member' and no extension method 'name' accepting a first argument of type 'type' could be found (are you missing a using directive or an assembly reference?).

This error occurs when you try to call a method or access a class member that does not exist.

The following example generates CS1061 because TestClass1 does not have a DisplaySomething method. It does have a method that is called WriteSomething. Perhaps that is what the author of this source code meant to write.

// cs1061.cs  
public class TestClass1  
{  
    // TestClass1 has one method, called WriteSomething.  
    public void WriteSomething(string s)  
    {  
        System.Console.WriteLine(s);  
    }  
}  
  
public class TestClass2  
{  
    // TestClass2 has one method, called DisplaySomething.  
    public void DisplaySomething(string s)  
    {  
        System.Console.WriteLine(s);  
    }  
}  
  
public class TestTheClasses  
{  
    public static void Main()  
    {  
        TestClass1 tc1 = new TestClass1();  
        TestClass2 tc2 = new TestClass2();  
        // The following call fails because TestClass1 does not have   
        // a method called DisplaySomething.  
        tc1.DisplaySomething("Hello");      // CS1061  
  
        // To correct the error, change the method call to either   
        // tc1.WriteSomething or tc2.DisplaySomething.  
        tc1.WriteSomething("Hello from TestClass1");  
        tc2.DisplaySomething("Hello from TestClass2");  
    }  
}  

Classes and Structs
Extension Methods

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