Static data members and static member function, C/C++ Programming

Assignment Help:

Static Data Members:

A data member inside the class can construct as static data member.   There are few

guidelines to be followed when declaring static data member.

  • It is declared as a private data member.
  • Only one copy of the static data member is created any numbers of objects are created from that class. Therefore the static data member will be same for all the objects created.
  • The static member must be defined outside the class like function with class name.
  • The static member can be initialized in the definition and can be used only within its class.

 

The following program will give clear difference between static data count and regular data number members.  The static data is common to all objects but regular data is unique to its object.

 

class item

{int number; static int count; public:

void getdata()

{++count;

number=count;

}

void putdata(void)

{cout<<"Count is "<

cout<<"Number is "<

}

};

int item::count=0;

int main()

 

 

{           clrscr();

item x,y,z; //Three object produced from class item x.getdata();

y.getdata();

z.getdata();

x.putdata(); The count is 3 and number is 1

y.putdata(); The count is 3 and number is 2 z.putdata(); The count is 3 and number is 3

return 0;

}

 

Static Member Function:

The static member function can be specified like static data member.  It works asc a static member data except the static member data is used in static member function.

Rules of Static Member function are given below:

  • The static member function can read static data member only from its class.
  • The static member function is called using class name not object name. class_name::static_function_name( ); It can also be called using object.static_fun( ).

 

The given program will illustrate how the static member function is worked.

 class find

{static int count;

int code;

public:

static void showcount(void)

{cout<<"Count is " <

}

void setcode(void)

{code = ++count;

}

void setcount(void)

{ cout<<"Code is " <

}

};

int find ::count=0;

int main()

{clrscr();

find x,y,z;

x.setcode(); // Code and count is 1. y.setcode(); //Code and count is 2 find::showcount(); //Count is 2

 

z.setcode(); //Code and count is 3 find::showcount(); //Count is 3

 

x.setcount(); // Code is 1 for object x.

 

 

 

 

y.setcount(); // Code is 2 for object y. z.setcount(); // Code is 3 for object z.

 

x.setcode(); // Code and count is 4. y.setcode(); //Code and count is 5 z.setcode(); //Code and count is 6 find::showcount(); //Count is 6

//The value of code will increase from its previous value of that object.

x.setcount(); // Code is 4 for object x. y.setcount(); / Code is 5 for object x. z.setcount(); // Code is 6 for object x.

return 0;

}

 

Since the count is declared as static it has only one copy irrespective of number of objects created.   When static count function called again and again it will increase count for all the objects created simultaneously therefore the count will be uniform for all object, but for the data member code it is unique for each object created because it is not a static data member.  Therfore from the above example there will only one value for count data member irrespective of number of objects constructed since it is a static data member, where as for code data member the value will be different for each object.


Related Discussions:- Static data members and static member function

Write a fragment of code that declares a variable, (a) Write a fragment of ...

(a) Write a fragment of code that declares a variable colSp of type ColourSpot, and then moves it to the point (3, -4), and sets its colour to Green. (b) A function QU8 is speci

C++ program, Receive 3 numbers and display them in ascending order from sma...

Receive 3 numbers and display them in ascending order from smallest to largest ed#

Explain automatic variables, Automatic Variables Automatic variables ar...

Automatic Variables Automatic variables are variable which are explained within the functions. They lose their value when the function terminates. It can be accessed only in th

Create cpp code for identify objects and their relationships, You are setti...

You are setting up an information system for a DVD Rental Company called Box office. The new system need to hold information about customers and DVDs rentals, payments and fines. C

Is always the default constructor for fred fred::fred()?, Is always the def...

Is always the default constructor for Fred Fred::Fred()?

Program decision making instructions, Within programs we very often want to...

Within programs we very often want to execute a different section of code, depending upon various conditions within C the If statement is used to achieve this. The If statement con

Explain register variable, Explain Register Variable Computers have int...

Explain Register Variable Computers have internal registers, which are used to keep data temporarily, before any operation can be performed. Intermediate results of the calcula

Define the relational operator in c language, Define the Relational Operato...

Define the Relational Operator in c language? The Relational operators refer to the relationships that values can have with one another and they are used to compare two operand

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd