Assignment Operator and Operator Overloading in Object-Oriented Programming, Exercises of Object Oriented Programming

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Object-Oriented Programming

(OOP)

Lecture No. 18

Assignment operator ►Modifying:^ class String{

… public:… void operator =(const String &);};

Assignment operator^ int main(){

String str1(“ABC");String str2(“DE”), str3(“FG”);str1 = str2;

// Valid…

str1 = str2 = str3;

// Error…

return 0;}

Assignment operator ►str1=str2=str

is resolved as:

str1.operator=(str2.operator=

(str3))

Return type isvoid. Parametercan’t be void

Assignment operator String

&^ String

::^

operator

=^ (const

String

rhs){

size

=^ rhs.size; delete

[]^

bufferPtr; if(rhs.size

!=^

bufferPtr

=^ new

char[rhs.size+1];

strcpy(bufferPtr,rhs.bufferPtr);} else^ bufferPtr

=^ NULL;

return

*this;

Assignment operator^ void

main(){String

str1(“AB"); String

str2(“CD”),

str3(“EF”);

str

=^ str2; str

=^ str

=^ str3;

Now

valid…

Assignment operator^ int

main(){String

str1("Fakhir");

//^

Self

Assignment

problem…

str

=^

str1;

return

… // size = rhs.size;// delete [] bufferPtr;…

Assignment operator ►Result of

str1 = str1 str

Fakhir

Assignment operator ►Now self-assignment is properly handled:^ int

main(){String

str1("Fakhir");

str

=^

str1;

return

Assignment operator ►Solution: modify the

operator=

function as follows:^ class String{

… public:… const

String & operator=

(const String &);

Assignment operator^ But we can do the following withprimitive types:^ int main(){

int a, b, c;(a = b) = c;return 0;}

Other Binary operators^ ►Overloading

operator:

class Complex{double real, img;public:Complex & operator+=(const Complex &

rhs);

Complex & operator+=(count double &

rhs);

Other Binary operators^ Complex & Complex::operator +=

(const double & rhs){

real = real + rhs;return * this;}

Other Binary operators^ int main(){

Complex c1, c2, c3;c1 += c2;c3 += 0.087;return 0;}