Pointer declaration for member function, C/C++ Programming

Pointer declaration for member function:

Method 1: When Class is not declared as pointer

M n;

void(M::*pf)(int,int)=&M::setxy; (n.*pf)(10,20);

n.setxy(10,20); //is same as prior statement.

Remember in C the syntax is (*function_name)(arguments); in C++ the only difference is the function should be member function of a class therefore the function should be identified by the class with           help      of              scope    operator         ::,             thus             the     syntax   for       C++          is (class_name::*function_name)(argument);

 

 

Method 2: When Class is declared as pointer

M *op;

op=&n;

(op->*pf)(30,40);

 

The difference from the first method is the class is also declared as pointer class, in such case the dereferencing operator -> is used (pointer_class_name:_*pointer_function_name)(argument);

 

The following example will give clear understanding of pointer to members both function members and data member.

 

class M

{int x, y;

public:

void setxy(int a, int b)

{x=a;

y=b;

}

friend int sum(M m);

};

int sum(M m)

{//Declaring pointer to data member int M::*px;

px=&M::x; int M::*py; py=&M::y;

//Declaring class as pointer

M *pm;

pm=&m;

int S,S1,S2;

//Two ways of reading through pointer

S1=m.*px; //object_name.*pointer-to-member function

S2=pm->*py;//pointer-to-object->*pointer-to-member function

S=S1+S2;

//S=m.x+m.y; //is same as prior statement without pointer.

return S;

}

int main()

{clrscr();

M n; void(M::*pf)(int,int)=&M::setxy; (n.*pf)(10,20);

n.setxy(10,20); //is same as prior statement. cout<<"SUM is "<<sum(n)<<"\n";

 

M *op;

 

 

op=&n;

(op->*pf)(30,40);

//n.setxy(30,40); //is same as prior statement. cout<<"Sum is "<<sum(n);

return 0;

}

Posted Date: 9/20/2012 8:03:30 AM | Location : United States







Related Discussions:- Pointer declaration for member function, Assignment Help, Ask Question on Pointer declaration for member function, Get Answer, Expert's Help, Pointer declaration for member function Discussions

Write discussion on Pointer declaration for member function
Your posts are moderated
Related Questions
Explain the Symbolic Constants in c language? Symbolic constants are the constants of any type that declared by using the #define compiler directive and it is a preprocessor di

A: No.       While realloc() need to copy the allocation, this uses a bitwise copy operation, that will tear several C++ objects to shreds. C++ objects must be allowed to copy t

electricity biil code


There is a pebble merchant. He sells the pebbles, that are used for shining the floor. His main duty is to take the length of the room’s sides. But he sometimes mistakes doing that

A: The answer to this lies actually, how they used. Along ++i(PreIncrement) the variable is incremented and new value is returned. Thus it needs one instruction to increment the va

Static Variables Static variables have the similar scope s automatic variables, but, unlike automatic variables, static variables retain their values over number of function ca

(RationalNumber Class) A rational number is a number that can be represented as the quotient of two integers. For example, 1/3, 5/7, 7/2, and so forth are rational numbers (By 2/1

Question 1 Explain the concept of constructors and destructors in C++ with programming examples Question 2 Explain the concepts and applications of multiple inheritance and v

Write a program to calculate the timetable for numbers 1 -> 10 and display them as follows. Your solution should use for do loops      #include stdio.h void main() {    char p