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Passing an argument by value means that the method that receives the argument can not change the value of the argument. Passing an argument by reference means that the method that receives the argument can change the value of the incoming argument, and the argument may be changed in the orignal calling method.
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What is the name given to the technique whereby a function argument can be modified by passing a pointer to the argument?
Call_by_reference
What argument passes in a method that will reference the content and can change the variable in the method?
That is called passing an argument by reference.
Does C even have pass by reference?
Strictly speaking, no. All arguments in C are passed by value. However, when the argument being passed is a memory address, although the address itself is passed by value, we're effectively passing the object that resides at that address -- by reference. Thus when a function's formal argument is a pointer variable (of any type), then it can be taken as read that the function is using the pass by reference semantic rather than the pass by value semantic. Nevertheless, it is important to keep in mind that the formal argument is assigned a copy of the actual argument and is therefore being passed by value.
What are the advantages of pass by reference as compared to pass by value?
Call by reference, particularly when applied to objects, because call by value automatically invokes an object's copy constructor, which is seldom desirable when passing objects into functions.
Where to use overloading?
Default arguments are often considered to be optional arguments, however a default argument is only optional in the sense that the caller need not provide a value for it. The function must still instantiate the argument and must assign the appropriate value to it so, insofar as the function is concerned, the argument is not optional. To implement a function with a truly optional argument, we can define two overloads of that function, one that accepts the optional argument (without specifying a default value) and one that does not accept the argument. In this way we can define two different implementations, one that uses the argument and one that does not. void f (); // implementation that does not use the argument void f (int); // implementation that does use the argument In many cases, a default argument incurs no significant overhead over that of overloading. Thus we'd only use overloading to implement an optional argument where there is a significant overhead incurred by a default argument. Even so, we must also be aware that by eliminating the overhead within the function itself we may simply be passing that overhead back to the callers, because some or all of them would then have to decide which overload to call, resulting in code duplication that would likely be best handled by the function itself.
