member-access-operators-dot-and.md

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Learn more about: Member access operators: '.' and '->'	Member access operators: '.' and '->'	12/04/2021	. ->	member access, expressions operators [C++], member access dot operator (.) -> operator member access, operators postfix operators [C++] . operator member access	f8fc3df9-d728-40c5-b384-276927f5f1b3

Member access operators: . and ->

Syntax

postfix-expression:
  postfix-expression . template_opt id-expression
  postfix-expression -> template_opt id-expression

Remarks

The member access operators . and -> are used to refer to members of struct, union, and class types. Member access expressions have the value and type of the selected member.

There are two forms of member access expressions:

1. In the first form, postfix-expression represents a value of struct, class, or union type, and id-expression names a member of the specified struct, union, or class. The value of the operation is that of id-expression and is an l-value if postfix-expression is an l-value.

2. In the second form, postfix-expression represents a pointer to a struct, union, or class, and id-expression names a member of the specified struct, union, or class. The value is that of id-expression and is an l-value. The -> operator dereferences the pointer. The expressions e->member and (*(e)).member (where e represents a pointer) yield identical results (except when the operators -> or * are overloaded).

Example

The following example demonstrates both forms of the member access operator.

// expre_Selection_Operator.cpp
// compile with: /EHsc
#include <iostream>
using namespace std;

struct Date {
   Date(int i, int j, int k) : day(i), month(j), year(k){}
   int month;
   int day;
   int year;
};

int main() {
   Date mydate(1,1,1900);
   mydate.month = 2;
   cout  << mydate.month << "/" << mydate.day
         << "/" << mydate.year << endl;

   Date *mydate2 = new Date(1,1,2000);
   mydate2->month = 2;
   cout  << mydate2->month << "/" << mydate2->day
         << "/" << mydate2->year << endl;
   delete mydate2;
}

2/1/1900
2/1/2000

See also

Postfix expressions
C++ built-in operators, precedence, and associativity
Classes and Structs
Structure and union members