Introduction to Introduction to ProgrammingProgramming

Lecture 32Lecture 32

In Last LectureIn Last Lecture– What is operator overloading ?What is operator overloading ?– Overload operatorsOverload operators

We also saw theWe also saw the– Binary OperatorsBinary Operators– Unary OperatorsUnary Operators– Member and Non-member Member and Non-member operatorsoperators

ExampleExample

Complex operator - ( Complex c ) ;Complex operator - ( Complex c ) ;

Complex Complex :: operator - ( Complex c )Complex Complex :: operator - ( Complex c )

{{

Complex Temp ;Complex Temp ;

Temp.real = real - c.real ;Temp.real = real - c.real ;

Temp.imag = imag - c.imag ;Temp.imag = imag - c.imag ;

return Temp ;return Temp ;

}}

ExampleExample

ExampleExample

void operator -= ( Complex c ) ;void operator -= ( Complex c ) ;

void Complex :: operator -= ( Complex c )void Complex :: operator -= ( Complex c )

{{

real -= c.real ;real -= c.real ;

imag -= c.imag ;imag -= c.imag ;

}}

ExampleExample

Date operator + ( int Date operator + ( int i ) ;i ) ;

Date Date :: operator + ( int days )Date Date :: operator + ( int days ){{

Date Temp ;Date Temp ; int toHold ;int toHold ;

int daysInThisMonth = 0 ;int daysInThisMonth = 0 ; daysInThisMonth = daysInMonth ( month ) ;daysInThisMonth = daysInMonth ( month ) ; toHold = days ;toHold = days ;

ExampleExample

if ( ( day + days ) >= daysInThisMonth )if ( ( day + days ) >= daysInThisMonth ) {{ Temp.month = month + 1 ;Temp.month = month + 1 ; if ( Temp.month > 12 )if ( Temp.month > 12 ) {{ Temp.day = 1 ;Temp.day = 1 ; Temp.month = 1 ;Temp.month = 1 ; Temp.year = year + 1 ;Temp.year = year + 1 ; }}

ExampleExample

elseelse {{ toHold = day + days ;toHold = day + days ; if ( toHold > daysInThisMonth )if ( toHold > daysInThisMonth ) {{ Temp.day = toHold - daysInThisMonth ;Temp.day = toHold - daysInThisMonth ; }} Temp.year = year ;Temp.year = year ; }} }}

ExampleExample

elseelse {{ Temp.day = days + day ;Temp.day = days + day ; Temp.month = month ;Temp.month = month ; Temp.year = year ;Temp.year = year ; }} return Temp ;return Temp ;}}

ExampleExample

Unary Unary OperatorOperator

i ++i ++

i --i --

date += 1 ; date += 1 ; Same asSame asdate ++ ;date ++ ;

Date operator++ Date operator++ ( ) ;( ) ;

Unary Unary Member Member OperatorOperator

ExampleExamplevoid Date :: operator ++ ( )void Date :: operator ++ ( ){{ if ( day == daysOfMonth ( day , month , year ) )if ( day == daysOfMonth ( day , month , year ) ) {{

if ( month < 12 )if ( month < 12 ){{

day = 1 ;day = 1 ;month ++ ;month ++ ;

}}elseelse{{ day = 1 ;day = 1 ; month = 1 ;month = 1 ;

year ++ ;year ++ ; }} else else

day ++ ;day ++ ;} }

ExampleExampleDate Date :: operator + ( int days )Date Date :: operator + ( int days ){{ Date Temp ;Date Temp ;

for ( i = 1 ; i < days ; i ++ )for ( i = 1 ; i < days ; i ++ )++ ++ Temp Temp ;;

return Temp ;return Temp ;

}}

days = 5

Code Code Reuse Reuse

Comparison OperatorComparison Operator<<

>>

<=<=

>=>=

====

boolbool

bool operator > ( Date d ) bool operator > ( Date d ) ;;

ExampleExample

Date d1 , d2 ;Date d1 , d2 ;

if ( d1 > d2 )if ( d1 > d2 )

Date date ;Date date ;

date + 5 ;date + 5 ;

ExampleExample

ExampleExample

5 + date ;5 + date ;

InterfacInterfacee