This document discusses operator overloading and type conversion in C++. It defines operator overloading as providing new definitions for most C++ operators in relation to a class. It covers overloading unary operators like minus and binary operators like addition. Friend functions can also be used to overload binary operators. Rules for operator overloading include only existing operators can be overloaded and some operators cannot be overloaded. Type conversion automatically converts the type on the right side of an assignment to the type on the left. Constructors can be used to convert basic types to class types.

1. D.SHANMUGAPRIYA
I- M.Sc(IT)
OPERATOR OVERLOADING AND
TYPE CONVERSION

2. OPERATOR OVERLOADING AND
TYPE CONVERSION
 INTRODUCTION
 DEFINING OPERATOR OVERLOADING
 OVERLOADING UNARY OPERATORS
 OVERLOADI NG BINARY OPERATORS
 OVERLOADING BINARY OPERATORS USING
FRIENDS
 SOME OTHER OPERATOR OVERLOADING
EXAMPLES
 RULES FOR OVERLOADING OPERATORS
 TYPE CONVERSION

3. INTRODUCTION
Operator overloading is one of the many
exciting features of the C++ language.
Operator overloading provides a flexible option
for the creation of new definition for most of the
C++ operators.
Class member access operator(.,.*)
Scope resolution operator(::)
Size operator(size of)
Conditional operator(?:)

4. DEFINNING OPERATOR
OVERLOADING
We must specify what it means in relation to the class
to which the operator is applied.
Syntax:
Return type classname::operator op(arglist)
{
function body//task defined
}
 Operator functions must be either member functions or friend
functions:
 vector operator+(vector);//vectoraddition
 Vector operator-(vector)://unary minus

5. CONTINUE….
 Friend vector operator+(vector;vector); //vector addition
 Friend vector operator-(vector); //unary minus
 Vector operator-(vector&a); //subtraction
 Int operator==(vector,vector); //comparison
 The process of overloading involves the following steps:
 Create a class that defines the datatype that is to be used in the
overloading operation.
 Declare the operator functions operator op() in the public part of the
class.
 UNARY OPERATOR=X OP Y
 BINARY OPERATOR=OPERATOR OP(X)

6. OVERLOADING UNARY
OPERATORS
 A minus operator when use as a unary takes just one
operand.
 Remember a statement like
 It is possible to overload a unary minus operator using a friend
function as follows:
Friend void operator-(space&s);
void operator-(space&s)
S2=-S1;
S.X=-S.X;
S.Y=-S.Y;
S.Z=-S.Z;

7. Example:

8. OVERLOADING BINARY
OPERATORS
 The same mechanism can be used to overload a binary
operator.
 C1 takes the responsibility of invoking the function
and c2 plays the role of an argument that is passed to
the function.
 Both the objects are available for the function.
C=SUM(A,B);
C3=C1.OPERATOR+(C2);
TEMP.X=X+C.X;

9. Example:

10. IMPLEMENTED OF THE OVERLOAD BINARY
OPERATOR:

11. OVERLOADING BINARY
OPERATORS USING FRIENDS
 Friend functions may be used in the place of member functions
for overloading a binary operator.
1) Replace the member function declartion by the friend
function declaration
2) [friend complex operation+(complex,complex);
3) Redefine the operator function as followa:
[complex opearor+(complex a,complex b)
{
return complex((a.x+b.x),(a.y+b.y));
}
In this case the statement
C3=C1+C2;
C3=OPERATOR+(C1+C2);

12. MANIPULATION OF STRINGS
USING OPERATORS
 ANSI C implements strings using character arrays,pointers and string
functions.
 EXAMPLE:
 Thus we must create string objects that we can hold these two pieces of
information.
Class string
{
Char*p;
Int len;
Public:
}
String3=string1+string2;
If(string 1>=string2)string=string1;

13. MATHEMATICAL OPERATIONS ON
STRING:

14. SUB TOPICS
OVERLOADING THE SUBSCRIPT OPERATOR
o The subscript operator is normally used to access and
modify a specific element in an array.
OVERLOADING THE POINTER TO MEMBER -
>OPERATOR:
o The pointer to member operator is normally used to
conjunction with an object pointer to access any of the
objects member.

15. RULES FOR OVERLOADING
OPERATOR
 There are certain restrictions and limitations in
overloading them,some of them are listed below
Only existing operators can be overloaded
Overloaded operators follow the syntax rules of the
original operators.
There are some operators that cannot be overloaded.
SIZE OF SIZE OF OPERATOR
. Membership operator
.* pointer to member operator
:: scope resolution operator
?: conditional operator

16. TYPE CONVERSION
 The type of data to the right of an assignment
operator is automatically converted to the type of
the variable on the left.
BASIC TO CLASS TYPE:
1) It may be recalled that the use of constructor was
illustrated in a number of examples to initialize
objects.
int m;
float x=3.14159;
m=x;

17. Continue…
 Following constructor:
string::string(char*a)
{
length=strlength(a);
p=new char[length+1];
strcpy(p,a);
}
The statement
s1=string(name 1);
First converts name1 from char* type and then values the
assign the strings type values to the objects S1
S2=Name 2;

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