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
Problem: (a) Distinguish between a class and an object. (b) Define instantiation. (c) What is the importance of the "this" variable in java. (d) What is encapsulation?


Write a program to get the largest element in an array using Function? # include int largest(int b[],int); main() { int lar,a[5]={12,2,36,40,5}; lar=largest(a,n); printf("

Requirements: 1.  This assignment as well as other assignments in this class must be finished on Windows operating system. 2.  Zip your program and submit the zip file on ANG

Operation on list - c++ program: Write a program in c to Insert value on list and list iteration. typedef struct item *node_ptr; struct item {                   int e

i need expression and its types with example programs in c++


I want Packet capture analysis Project Description: Need assistance in debugging some packet capture Skills required is C Programming

What are Arrays? Numerous applications require the processing of multiple data items that have identical characteristics. In such circumstances it is frequently convenient to p

Write a program to find the area under the curve y = f(x) between x = a and x = b, integrate y = f(x) between the limits of a and b. The area under a curve between two points can b