Page 157 - DCAP404 _Object Oriented Programming

Object-oriented Programming

Notes Most programmers find the friend function version easier to read than the member function
version, because the parameters are listed explicitly. Furthermore, the friend function version
can be used to overload some things the member function version can not. For example, friend
operator+(int, cCents) can not be converted into a member function because the leftmost parameter
is not a class object.
However, when dealing with operands that modify the class itself (eg. operators =, +=, -=, ++,
-, etc…) the member function method is typically used because C++ programmers are used to
writing member functions (such as access functions) to modify private member variables. Writing
friend functions that modify private member variables of a class is generally not considered
good coding style, as it violates encapsulation.

Self Assessment

Fill in the blanks:
10. When the function defined for the binary operator overloading is a friend function, then
it uses …………………… arguments.
11. Operator overloading adds new functionality to its existing ………………... .
12. The program will be efficient and readable only if ……………………….. is used only when
necessary.
13. Binary operator overloading, as in unary operator overloading, is performed using a
………………………… operator.
7.5 Manipulation of Strings using Operator Overloading

ANSI C implements strings using character assays, pointers and string functions. There are no
operators for manipulating the strings. There is no direct operator that could act upon the
strings. Although, these limitations exist in C++ as well, it permits us to create our own definitions
of operators that can be used to manipulate the strings very much similar to the decimal numbers
for e.g. we shall be able to use the statement like
String3 = string1 + string2;
The following program to overload the ‘+’ operator to append one string to another

#include<iostream.h>
#include<conio.h>
class str
{
char *name;
public:
str();

str(char *);
void get();
void show();
str operator + (str);
};

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