Operator Overloading

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Chapter 6

• Operator Overloading

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Outlines

• 6.1 Fundamentals of Operator Overloading
• 6.2 Operator Functions
• 6.3 Overloading Binary Operators
• 6.4 Overloading Unary Operators
• 6.5 Overloading the Stream Operators
• 6.6 Case Study AC Current Calculator

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Introduction

• The use of operators enables programmers to write
  concise expressions and produce clearer code.
• It provides a tool called operator overloading
  that enables programmers to use existing
  operators to manipulate objects of their own
  classes.

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FUNDAMENTALS OF OPERATOR OVERLOADING

• Operator overloading is a special type of
  function overloading.
• It is a process in which programmers instruct the
  C compiler to apply existing operators in an
  effort to manipulate objects of their own
  abstract data types.
• An operator is overloaded if it can be used to
  perform multiple operations.
• The operator
• used to multiply two values of built in types
  such as int, ,float, or double,
• to declare or dereference a pointer.
• It can be further overloaded to multiply two
  objects of user defined types.

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Example

• int x3, y5, z
• zxy // multiplication
• float f3.4
• float fptf // is used to declare a pointer
• fpt5.6 // is used to dereference the pointer
• Current c1(1,45), c2(2,0), c3
• c3c1c2
• // is used to perform a user defined operation
• //relative to the Current class

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Operator

• Please note that there are four operators that
  can be overloaded in both unary and binary forms
• -
• Five operators cannot be overloaded
• . . ? sizeof

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Operator

• Operators that can be overloaded
• new new delete delete
• - /
• ! lt gt
• - /
• ltlt gtgt ltlt gtgt ! lt
• gt -- , -gt
• -gt ()

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• When an operator is overloaded, it keeps its
  original meanings and gains an additional meaning
  through the overloading process that is relative
  to the class for which it is defined.
• Most of the operators in C can have only one
  form