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C# 3.0 introduced type inference, allowing the type specifier of a variable declaration to be replaced by the keyword var, if its actual type can be statically determined from the initializer. This reduces repetition, especially for types with multiple generic type-parameters , and adheres more closely to the DRY principle.
The specification for pass-by-reference or pass-by-value would be made in the function declaration and/or definition. Parameters appear in procedure definitions; arguments appear in procedure calls. In the function definition f(x) = x*x the variable x is a parameter; in the function call f(2) the value 2 is the argument of the function. Loosely ...
A reference variable, once declared and bound, behaves as an alias of the original variable, but it can also be rebounded to another variable by using the reference assignment operator = ref. The variable itself can be of any type, including value types and reference types, i.e. by passing a variable of a reference type by reference (alias) to ...
Call by reference (or pass by reference) is an evaluation strategy where a parameter is bound to an implicit reference to the variable used as argument, rather than a copy of its value. This typically means that the function can modify (i.e., assign to ) the variable used as argument—something that will be seen by its caller.
Some languages assist this task by offering constructs to handle the initializedness of variables; for example, C# has a special flavour of call-by-reference parameters to subroutines (specified as out instead of the usual ref), asserting that the variable is allowed to be uninitialized on entry but will be initialized afterwards.
For a simple type like a number these conventions are relatively clear. Passing ByRef allows the procedure to modify the passed variable whereas passing ByVal does not. For an object, semantics can confuse programmers since an object is always treated as a reference. Passing an object ByVal copies the reference; not the state of the object. The ...
Even if the variable to capture is non-final, it can always be copied to a temporary final variable just before the class. Capturing of variables by reference can be emulated by using a final reference to a mutable container, for example, a one-element array. The local class will not be able to change the value of the container reference, but ...
Such a variable can be address without an explicit pointer reference (xxx=1;, or may be addressed with an explicit reference to the default locator (ppp), or to any other pointer (qqq->xxx=1;). Pointer arithmetic is not part of the PL/I standard, but many compilers allow expressions of the form ptr = ptr±expression .