Compiler Error CS0120
An object reference is required for the nonstatic field, method, or property 'member'
In order to use a non-static field, method, or property, you must first create an object instance. For more information about static methods, see Static Classes and Static Class Members (C# Programming Guide). For more information about creating instances of classes, see Instance Constructors (C# Programming Guide).
The following sample generates CS0120:
// CS0120_1.cs
public class MyClass
{
// Non-static field
public int i;
// Non-static method
public void f(){}
// Non-static property
int Prop
{
get
{
return 1;
}
}
public static void Main()
{
i = 10; // CS0120
f(); // CS0120
int p = Prop; // CS0120
// try the following lines instead
// MyClass mc = new MyClass();
// mc.i = 10;
// mc.f();
// int p = mc.Prop;
}
}
CS0120 will also be generated if there is a call to a non-static method from a static method, as follows:
// CS0120_2.cs
// CS0120 expected
using System;
public class MyClass
{
public static void Main()
{
TestCall(); // CS0120
// To call a non-static method from Main,
// first create an instance of the class.
// Use the following two lines instead:
// MyClass anInstanceofMyClass = new MyClass();
// anInstanceofMyClass.TestCall();
}
public void TestCall()
{
}
}
Similarly, a static method cannot call an instance method unless you explicitly give it an instance of the class, as follows:
// CS0120_3.cs
using System;
public class MyClass
{
public static void Main()
{
do_it("Hello There"); // CS0120
}
private void do_it(string sText)
// You could also add the keyword static to the method definition:
// private static void do_it(string sText)
{
Console.WriteLine(sText);
}
}