Use the const keyword in C#. The const (read: constant) keyword in C# is used to define a constant variable, i.e., a variable whose value will not change during the lifetime of the program.

Prior to C++11 the .real() and .imag() methods were specified to return non-reference values, so it was a non-standard extension that allowed you to assign to the results of these methods ...

Additionally, because a value type is always “copied by value,” when you pass a value type as a parameter to a method or assign it to a variable, the entire data is copied.