Skip to main content

Adding Flexibility to Operators while Overloading them

  class_name class_name::operator+(int x)
    class_name temp;

    temp.a = a + x;
    temp.b = b + x;

    return temp;

With reference to the above operator function and supposing that ‘ob’ is an object of the class to which this function belongs; Is the statement below legal:

ob2 = ob1 + 100;

Yes, but what about the following statement:

ob2 = 100 + ob1;

Surely this won’t work!

100 is an integer constant and has no ‘+’ operator that could add it with user-defined types (object ‘ob’).

This certainly is a shortcoming, since often we don’t really care which operand is where (as in addition and multiplication) and we order the operands as necessary (as in subtraction and division).

To overcome this we can overload two-two versions of these operators as friend, one for ‘integer + object’ type and the other for ‘object + integer’ type.

So, for example for addition we have to overload the ‘+’ operator twice as below:

  friend class_name operator+(class_name,int);
  friend class_name operator+(int,class_name);

Similarly we have to overload other operators.

The program below illustrates this concept:

  // Program to illustrate
  // the overloading of
  // flexible addition
  // and subtraction
  // operators
  #include <iostream.h>

  class myclass
    int a;
    int b;

    myclass(int x,int y){a=x;b=y;}
    void show()

    // object + int form
    friend myclass operator+(myclass,int);
    friend myclass operator-(myclass,int);

    // int + object form
    friend myclass operator+(int,myclass);
    friend myclass operator-(int,myclass);

  myclass operator+(myclass ob,int x)
    myclass temp;

    temp.a = ob.a + x;
    temp.b = ob.b + x;

    return temp;

  myclass operator-(myclass ob, int x)
    myclass temp;

    temp.a = ob.a - x;
    temp.b = ob.b - x;

    return temp;

  myclass operator+(int x, myclass ob)
    // does the same thing
    // because in addition
    // it doesn't matters
    // which operand is where
    myclass temp;

    temp.a = x + ob.a;
    temp.b = x + ob.b;

    return temp;

  myclass operator-(int x, myclass ob)
    myclass temp;

    temp.a = x - ob.a;
    temp.b = x - ob.b;

    return temp;

  void main()
    myclass a(10,20);
    myclass b(100,200);

    a=a + 10;;

    b=100 + b;;

Related Articles:

Popular posts from this blog

Fix For Toshiba Satellite "RTC Battery is Low" Error (with Pictures)

RTC Battery is Low Error on a Toshiba Satellite laptop "RTC Battery is Low..." An error message flashing while you try to boot your laptop is enough to panic many people. But worry not! "RTC Battery" stands for Real-Time Clock battery which almost all laptops and PCs have on their motherboard to power the clock and sometimes to also keep the CMOS settings from getting erased while the system is switched off.  It is not uncommon for these batteries to last for years before requiring a replacement as the clock consumes very less power. And contrary to what some people tell you - they are not rechargeable or getting charged while your computer or laptop is running. In this article, we'll learn everything about RTC batteries and how to fix the error on your Toshiba Satellite laptop. What is an RTC Battery? RTC or CMOS batteries are small coin-shaped lithium batteries with a 3-volts output. Most laptops use

Creating a Simple Phone Book in PHP

This is a short follow-up of the post Storing and Retrieving Data from MySQL Database . Here we’ll expand the Phone Book Script that we’ve created to include the following three features: Use an efficient table structure to store data with proper INDEX (primary key) defined. Display previously stored phone numbers in different orders. Include a Search feature to let user easily find the person’s phone number he/she is seeking. To create efficient table Read the MySQL Data Types and Properties post to know more. We’ll create a table having an ID field having serial numbers auto_incremented. We’ll set it to be the primary key. We can do this with the help of the following SQL query: CREATE TABLE phno( id int AUTO_INCREMENT PRIMARY KEY , name varchar( 50 ) , phnum varchar( 20 ) ) Retrieving data in other orders For our table we’d easily be able to retrieve data in the following four orders: Newe

The Best Way(s) to Comment out PHP/HTML Code

PHP supports various styles of comments. Please check the following example: <?php // Single line comment code (); # Single line Comment code2 (); /* Multi Line comment code(); The code inside doesn't run */ // /* This doesn NOT start a multi-line comment block /* Multi line comment block The following line still ends the multi-line comment block //*/ The " # " comment style, though, is rarely used. Do note, in the example, that anything (even a multi-block comment /* ) after a " // " or " # " is a comment, and /* */ around any single-line comment overrides it. This information will come in handy when we learn about some neat tricks next. Comment out PHP Code Blocks Check the following code <?php //* Toggle line if ( 1 ) {      // } else {      // } //*/ //* Toggle line if ( 2 ) {      // } else {      // } //*/ Now see how easy it is to toggle a part of PHP code by just removing or adding a single " / " from th