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A Closer Look at Functions

This module continues our examination of the function. It discusses three of C++’s most important function-related topics: references, function overloading, and default arguments. These features vastly expand the capabilities of a function. A reference is an implicit pointer. Function overloading is the quality that allows one function to be implemented two or more different ways, each performing a separate task. Function overloading is one way that C++ supports polymorphism. Using a default argument, it is possible to specify a value for a parameter that will be automatically used when no corresponding argument is specified. We will begin with an explanation. | Module6 A Closer Look at Functions Table of Contents CRITICAL SKILL 6.1 Know the two approaches to argument passing.2 CRITICAL SKILL 6.2 How C Passes Arguments.2 CRITICAL SKILL 6.3 Using a Pointer to Create a Call-by-Reference.3 CRITICAL SKILL 6.4 Reference Parameters.4 CRITICAL SKILL 6.5 Returning References.9 CRITICAL SKILL 6.6 Independent References.12 CRITICAL SKILL 6.7 Function Overloading.13 CRITICAL SKILL 6.8 Default Function Arguments.26 CRITICAL SKILL 6.9 Function Overloading and Ambiguity.29 This module continues our examination of the function. It discusses three of C s most important function-related topics references function overloading and default arguments. These features vastly expand the capabilities of a function. A reference is an implicit pointer. Function overloading is the quality that allows one function to be implemented two or more different ways each performing a separate task. Function overloading is one way that C supports polymorphism. Using a default argument it is possible to specify a value for a parameter that will be automatically used when no corresponding argument is specified. We will begin with an explanation of the two ways that arguments can be passed to functions and the implications of both methods. An understanding of argument passing is needed in order to understand the reference. 1 C A Beginner s Guide by Herbert Schildt CRITICAL SKILL 6.1 Know the two approaches to argument passing In general there are two ways that a computer language can pass an argument to a subroutine. The first is call-by-value. This method copies the value of an argument into the parameter of the subroutine. Therefore changes made to the parameter of the subroutine have no effect on the argument used to call it. Call-by-reference is the second way a subroutine can be passed arguments. In this method the address of an argument not its value is copied into the parameter. Inside the subroutine this address is used to access the actual argument .