C++ Programming for Experienced Engineers/

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Pointer to Member Operators

Pointer to Member Operators

Educate yourself about accessing the structure members using pointer to member operators.

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Problem

Write a program to access the struct members using the pointer to member operators .* and ->*.

Sample run

Here’s what you should see when you run the program.

10      3.14
10      3.14
20      6.28
20      6.28
30      9.22
40      7.33
60      8.88

Coding solution

Here is a solution to the problem above.

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// Pointer to member operators
#include <iostream> 
struct sample 
{ 	
	int a ; 	
	float b ; 
} ;  
int main( ) 
{ 	
	sample so = { 10, 3.14f } ;
	
	int sample::*p1 = &sample::a ; 	
	float sample::*p2 = &sample::b ; 
	
	std :: cout << so.*p1 << "\t" << so.*p2 << std :: endl ;
	sample *sp ;
	sp = &so ;
	std :: cout << sp->*p1 << "\t" << sp->*p2 << std :: endl ;
	// we can even assign new values
	so.*p1 = 20 ;
	sp->*p2 = 6.28f ;
	std :: cout << so.*p1 << "\t" << so.*p2 << std :: endl ;
	std :: cout << sp->*p1 << "\t" << sp->*p2 << std :: endl ;
	sample soarr[ ] = {
		{ 30, 9.22f },
		{ 40, 7.33f },
		{ 60, 8.88f } 
		} ;
	for ( int i =0 ; i <= 2 ; i++ ) 		
		std :: cout << soarr[ i ].*p1 << "\t" << soarr[ i ].*p2 << std :: endl ;
	
	return 0 ; 
}

Explanation

To carry out the access and the ...