Constant function member in C++ programming

A constant function member can never modify any of its class’s data member.

const keyword to used to define constant function.

#include< iostream.h >

#include< conio.h >

class sample

{

private:

int count;

public:

sample()

{

count=0;

}

void change()

{

count=10;

}

void  show()const

{

count=12;/* this statement will show error in compile time */

cout<< "\nThe data member:"<< count;

}

};

void main()

{

clrscr();

sample sp1;

sp1.change();

sp1.show();

getch();

}