<!DOCTYPE html>

<html lang="en">

<head>

<meta charset="UTF-8" />

<meta name="viewport" content="width=device-width, initial-scale=1.0" />

<meta name="description" content="A multidimensional array is an array that is more than just a single row of

elements. It may have rows & columns, as in a 2D array, or may have 3D . All

elements must be of the same data type. C++ starts counting at zero for the

indexes of arrays.I" />

<meta name="keywords"

content="multidimensional arrays, multidimensional array,multidimensional arrays in cpp, multidimensional arrays in c++, multidimensional array in cpp, multidimensional array in c++, what is a multidimensional array, what are multidimensional arrays, what is a multidimensional array in cpp,what is a multidimensional array in c++,what are multidimensional arrays in cpp, what are multidimensional arrays in c++" />

<title>C++ Friend Function | C++ Tutorials | CodeMistic</title>

<!-- Google Ad -->

<script data-ad-client="ca-pub-5352867889640158" async

src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>

<!-- Google Tag Manager -->

<script>(function (w, d, s, l, i) {

w[l] = w[l] || []; w[l].push({

'gtm.start':

new Date().getTime(), event: 'gtm.js'

}); var f = d.getElementsByTagName(s)[0],

j = d.createElement(s), dl = l != 'dataLayer' ? '&l=' + l : ''; j.async = true; j.src =

'https://www.googletagmanager.com/gtm.js?id=' + i + dl; f.parentNode.insertBefore(j, f);

})(window, document, 'script', 'dataLayer', 'GTM-MCNC43J');</script>

<!-- End Google Tag Manager -->

<!-- Global site tag (gtag.js) - Google Analytics -->

<script async src="https://www.googletagmanager.com/gtag/js?id=G-YPTQSLH0XW"></script>

<script>

window.dataLayer = window.dataLayer || [];

function gtag() { dataLayer.push(arguments); }

gtag('js', new Date());

gtag('config', 'G-YPTQSLH0XW');

</script>

<!-- Favicon -->

<link rel="icon" type="img/png" href="../favicon.png" />

<!-- FONT AWESOME -->

<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.13.1/css/all.css"

integrity="sha384-xxzQGERXS00kBmZW/6qxqJPyxW3UR0BPsL4c8ILaIWXva5kFi7TxkIIaMiKtqV1Q" crossorigin="anonymous" />

<!-- FONTS -->

<link href="https://fonts.googleapis.com/css2?family=Kalam:wght@700&family=Ubuntu&family=Varela+Round&display=swap"

rel="stylesheet" />

<!-- Animate on scroll -->

<link rel="stylesheet" href="https://unpkg.com/aos@next/dist/aos.css" />

<!-- Bootstrap -->

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"

integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous" />

<!-- CSS -->

<link rel="stylesheet" href="../lang_styles.css" />

</head>

<body>

<!-- Google Tag Manager (noscript) -->

<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-MCNC43J" height="0" width="0"

style="display:none;visibility:hidden"></iframe></noscript>

<!-- End Google Tag Manager (noscript) -->

<!-- NAVIGATION BAR -->

<!-- <div class="container-fluid"> -->

<nav class="navbar fixed-top navbar-expand-xl navbar-dark">

<a class="navbar-brand" href="../index.html">CODEMISTIC</a>

<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"

aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">

<span class="navbar-toggler-icon"></span>

</button>

<div class="collapse navbar-collapse" id="navbarSupportedContent">

<ul class="navbar-nav ml-auto">

<li class="nav-item">

<a class="nav-link" href="../index.html">Home</a>

</li>

<li class="nav-item dropdown">

<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button"

data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">

Tutorials

</a>

<div class="dropdown-menu" aria-labelledby="navbarDropdown">

<a class="dropdown-item" href="../cpp.html">C++</a>

<div class="dropdown-divider"></div>

<a class="dropdown-item" href="../python.html">Python</a>

<div class="dropdown-divider"></div>

<a class="dropdown-item" href="../java.html">Java</a>

<div class="dropdown-divider"></div>

<a class="dropdown-item" href="../dsa.html">Data Structure and Algorithms</a>

<div class="dropdown-divider"></div>

<a class="dropdown-item" href="../tutorials.html">All Tutorials</a>

</div>

</li>

<li class="nav-item">

<a class="nav-link" href="../events.html">Events</a>

</li>

<li class="nav-item">

<a class="nav-link" href="../teen-code.html">Teen-Code</a>

</li>

<li class="nav-item">

<a class="nav-link" href="../campus.html">Campus Programme</a>

</li>

<!-- <li class="nav-item">

<a class="nav-link" href="https://docs.google.com/forms/d/e/1FAIpQLSc2O28YJpxQc6kh2tKpI_Lf5MwfwGXVnhMs0g5EEXobJ4Beeg/viewform?usp=sf_link" target="_blank">Contribute</a>

</li> -->

<li class="nav-item">

<a class="nav-link" href="../register.html">Join Our Community</a>

</li>

</ul>

</div>

</nav>

<!-- Accordion -->

<section class="lbar">

<div class="lang-img col-md-2">

<img src="../logo/cpp.png" alt="c++" class="cpp-img" style="margin-left: -25px;">

</div>

<ul id="accordion" class="accordion ml-5">

<li class=" collape in">

<div class="link">C++ Introduction<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="getting-started.html" class="closed">Getting Started</a>

</li>

<li>

<a href="variables-and-literals.html " class="closed">C++ Variables and Literals</a>

</li>

<li>

<a href="data-types.html" class="closed">C++ Data Types</a>

</li>

<li>

<a href="input-output.html" class="closed">C++ Basic I/O</a>

</li>

<li>

<a href="type-conversion.html" class="closed">C++ Type Conversion</a>

</li>

<li>

<a href="operators.html" class="closed">C++ Operators</a>

</li>

<li>

<a href="comments.html" class="closed">C++ Comments</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Flow Control<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="if-else.html" class="closed">C++ if...else</a>

</li>

<li>

<a href="for-loop.html" class="closed">C++ for Loop</a>

</li>

<li>

<a href="do-while.html" class="closed">C++ do...while Loop</a>

</li>

<li>

<a href="break-and-continue.html" class="closed">C++ break & continue</a>

</li>

<li>

<a href="switch-statement.html" class="closed">C++ switch Statement</a>

</li>

<li>

<a href="goto-statement.html" class="closed">C++ goto Statement</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Function<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="functions.html" class="closed">C++ Functions</a>

</li>

<li>

<a href="function-types.html" class="closed">C++ Function Types</a>

</li>

<li>

<a href="function-overloading.html" class="closed">C++ Function Overloading</a>

</li>

<li>

<a href="default-argument.html" class="closed">C++ Default Argument</a>

</li>

<li>

<a href="storage-class.html" class="closed">C++ Storage Class</a>

</li>

<li>

<a href="recursion.html" class="closed">C++ Recursion</a>

</li>

<li>

<a href="return-reference.html" class="closed">C++ Return Reference</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Arrays & String<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="arrays.html" class="closed">C++ Arrays</a>

</li>

<li>

<a href="multidimensional-arrays.html" class="closed">C++ Multidimensional Arrays</a>

</li>

<li>

<a href="function-arrays.html" class="closed">C++ Function and Array</a>

</li>

<li>

<a href="string.html" class="closed">C++ String</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Structures<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="structures.html" class="closed">C++ Structures</a>

</li>

<li>

<a href="structure-fuction.html" class="closed">Structure and Function</a>

</li>

<li>

<a href="pointers-structures.html" class="closed">C++ Pointers to Structure</a>

</li>

<li>

<a href="enumeration.html" class="closed">C++ Enumeration</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Object & Class<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="object-class.html" class="closed">C++ Objects and Class</a>

</li>

<li>

<a href="constructors.html" class="closed">C++ Constructors</a>

</li>

<li>

<a href="objects-fuctions.html" class="closed">C++ Objects & Function</a>

</li>

<li>

<a href="operator-overloading.html" class="closed">C++ Operator Overloading</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Pointers<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse">

<li>

<a href="pointers.html" class="closed">C++ Pointers</a>

</li>

<li>

<a href="pointers-arrays.html" class="closed">C++ Pointers and Arrays</a>

</li>

<li>

<a href="pointers-functions.html" class="closed">C++ Pointers and Functions</a>

</li>

<li>

<a href="memory-management.html" class="closed">C++ Memory Management</a>

</li>

</ul>

</li>

<li>

<div class="link">C++ Inheritance<i class="fa fa-chevron-down"></i>

</div>

<ul class="submenu collapse show">

<li>

<a href="inheritance.html" class="closed">C++ Inheritance</a>

</li>

<li>

<a href="inheritance-access-control.html" class="closed">Inheritance Access Control</a>

</li>

<li>

<a href="function-overriding.html" class="closed">C++ Function Overriding</a>

</li>

<li>

<a href="inheritence-types.html" class="closed">Inheritance Types</a>

</li>

<li>

<a href="friend-function.html" class="opened">C++ Friend Function</a>

</li>

<li>

<a href="virtual-function.html" class="closed">C++ Virtual Function</a>

</li>

<li>

<a href="templates.html" class="closed">C++ Templates</a>

</li>

</ul>

</li>

</ul>

</section>

<br>

<section class="para">

<!-- <div class="but mt-4">

&nbsp;&nbsp;&nbsp;&nbsp;<button class="btn btn-md btn-primary "><a href="../dsa.html"><i

class="fas fa-arrow-left "></i>&nbsp;Back to Index</a></button>

</div> -->

<!-- breadcrumb -->

<nav class="bdcrumb" id="bdcrumb" aria-label="breadcrumb">

<ul class="breadcrumb">

<li class="breadcrumb-item"><a href="../tutorials.html"><i class="fas fa-home"></i></a></li>

<li class="breadcrumb-item"><a href="../cpp.html">C++ Tutorials</a></li>

<li class="breadcrumb-item active" aria-current="page">C++ Friend Function</li>

</ul>

</nav>

<!-- breadcrumb ending -->

<!-- HEADING -->

<div class="wrapper">

<h3 class="pb-3 pt-3">Friend Function in C++</h3>

<p>In Object-Oriented Programming, a friend Function which is a "friend" of

a given class, is a special function that is given the same access as given

to the methods to private data and protected data. For example a

LinkedList class may be allowed to access private members of Node.</p>

<p>A friend Function is declared by the class that is granting access, so friend

functions are part of the class interface. A friend function of a class is

defined outside that class but it can access all private and protected

members of the class. Even though the prototypes for friend functions

appear in the class definition, friends are not member functions.In a

designed program the private and protected data can be accessed using

the function ,if the function is defined as a friend function.The compiler

can easily understand that the given function is a Friend Function ,the

compiler can do so by seeing a keyword called <code>friend</code>.</p>

<hr />

<h4 class="pt-3 pb-3">Properties of friend function</h4>

<ul>

<li>

Friend of the class can be member of some other class.

</li>

<li>

Friend of one class can be friend of another class or all the

other classes in single program, such type of friend is

called as Global Friend.

</li>

<li>

Friend can access the private member or protected

members of the class in which they are declared to be

friend, but they can use the members for a perticular

object.

</li>

<li>

Friends are non-members hence do not get <code>this</code> pointer

</li>

<li>

Friends, can be friend of more than one class, hence they

can be used for message passing between the classes.

</li>

<li>

Friend can be declared anywhere whether in public,

protected or private part of the class.

</li>

</ul>

<hr />

<h4 class="pt-3 pb-3">Declaration of friend function</h4>

<pre>class class_name

{

….… …… …….

friend return_type function_name(argument/s);

….…. …. ……

}</pre>

<p>Now, you can define the friend function as a normal function to access the data of

the class. No friend keyword is used in the definition.</p>

<pre>class className

{

... .. ...

friend return_type functionName(argument/s);

... .. ...

}

return_type functionName(argument/s)

{

... .. ...

// Private and protected data of className can be accessed from

// this function because it is a friend function of className.

... .. ...

}</pre>

<hr />

<p>Example 1: Working of friend function</p>

<pre>/* working of friend function.*/

#include &lt;iostream>

using namespace std;

class interspace {

private:

int centimeter;

public:

interspace(): centimeter(0) { }

//friend function

friend int addsixteen(interspace);

};

// friend function definition

int addsixteen(interspace i) {

//accessing private data from non-member function

i.centimeter += 16;

return i.centimeter;

}

int main() {

interspace I;

cout<<"interspace: "<< addsixteen(I);

return 0;

}</pre>

<p><strong>Output:</strong></p>

<pre>interspace: 16</pre>

<p>Here, friend function addsixteen() is declared inside interspace class. So, the private

data centimeter can be accessed from this function.A more meaningful use would to when

you need to operate on objects of two different classes.</p>

<p><strong>Example 2:</strong>Addition of member of two different classes using friend function</p>

<pre>include &lt;iostream>

using namespace std;

// forward declaration class P

class Q {

private:

int numberP;

public:

P(): numberP(25) { }

// friend function declaration

friend int add(P, Q);

};

class Q {

private:

int numberQ;

public:

Q(): number(8) { }

// friend function declaration

friend int add(P , Q);

};

// Function add() is the friend function of classes A and B

// that accesses the member variables numberP and numberQ

int add(P objectP, Q objectQ) {

return (objectP.numberP + objectQ.numberQ);

}

int main(){

P objectP;

Q objectQ;

cout<<"Sum: "<< add(objectP, objectQ);

return 0;

}</pre>

<p><strong>Output:</strong></p>

<pre>Sum: 33</pre>

<p>the above program, classes P and class Q have declared <code>add()</code> as a <strong>friend

function</strong>.

Thus, this function can access private data of both the class.Here, <code>add()</code> function adds the

private data <code>numberP</code> and <code>numberQ</code> of two objects <code>objectP</code> and

<code>objectQ</code> , and returns it to

the <strong>main</strong> function.</p>

</div>

<div class="but text-right">

<button class="btn btn-primary pull-right"><a href="virtual-function.html">Next Topic&nbsp;<i

class="fas fa-arrow-right "></i><br />C++ Virtual Function</a></button>

</div><br />

</section>

<!-- footer -->

<footer>

<div class="row footer">

<div class="logo">

<img src="../image.png" alt="" class="f-img">

<h5>LEARN CODE DISCUSS</h5>

</div>

<div class="footer-column ">

<ul class="footer-ul">

<li class="foot-header"><strong>CodeMistic</strong></li>

<li class="f-li"><a href="../index.html" class="f-links">Home</a></li>

<li class="f-li"><a href="../team.html" class="f-links">Our Team</a></li>

<li class="f-li"><a href="../terms-and-conditions.html" class="f-links">Terms of Service</a></li>

<li class="f-li"><a href="../privacy-policy.html" class="f-links">Privacy Policy</a></li>

</ul>

</div>

<div class="footer-column ">

<ul class="footer-ul ">

<li class="foot-header"><strong>LEARN</strong></li>

<li class="f-li"><a href="../cpp.html" class="f-links">C++</a></li>

<li class="f-li"><a href="../java.html" class="f-links">Java</a></li>

<li class="f-li"><a href="../python.html" class="f-links">Python</a></li>

<li class="f-li"><a href="../dsa.html" class="f-links">DSA</a></li>

</ul>

</div>

<div class="footer-column ">

<ul class="footer-ul ">

<li class="foot-header"><strong>CONTRIBUTE</strong></li>

<li class="f-li"><a

href="https://docs.google.com/forms/d/e/1FAIpQLSduxk_aP9M1lqUAebQJwRXiVm2ukmdgv3T7gjBpOsr_gdeOcQ/viewform?usp=sf_link"

class="f-links" target="_blank">Write an Article/Blog</a></li>

<li class="f-li"><a

href="https://docs.google.com/forms/d/e/1FAIpQLSc2O28YJpxQc6kh2tKpI_Lf5MwfwGXVnhMs0g5EEXobJ4Beeg/viewform?usp=sf_link"

class="f-links" target="_blank">Internships</a></li>

<li class="f-li"><a

href="https://docs.google.com/forms/d/e/1FAIpQLSe9nr_Aw0fGIqm3_xWhqEzTr3UWdOFz-pvKpQvkAsosORYq9w/viewform?usp=sf_link"

class="f-links" target="_blank">Videos</a></li>

<li class="f-li"><a

href="https://docs.google.com/forms/d/e/1FAIpQLScOW3hJjxxwzPYL4u51oboc4T1aDtIUEIRa20hKPKu4UlcZAA/viewform?usp=sf_link"

class="f-links" target="_blank">Donations/Funds</a></li>

</ul>

</div>

</div>

<div class="footer-links" style="text-align: center;">

<!-- <h7>Connect With Us</h7><br><br> -->

<a href="https://www.facebook.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-facebook "

style="color:#3b5998; "></i></a>

<a href="https://www.instagram.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-instagram "

style="color:#e95950; "></i></a>

<a href="https://www.twitter.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-twitter "

style="color:#8accf5; "></i></a>

<a href="https://www.linkedin.com/company/codemistic " target="_blank "><i

class="icons fa-2x fab fa-linkedin " style="color:#88b3ee; "></i></a>

<a href="https://t.me/codemistic " target="_blank "><i class="icons fa-2x fab fa-telegram "

style="color:#65adda; "></i></a>

<a href="https://www.youtube.com/channel/UCS1Iv_kkgQGDwoXtvrlwlag " target="_blank "><i

class="icons fa-2x fab fa-youtube " style="color:red; "></i></a>

<p class="foot mt-3">&#169 Copyright : <strong>CodeMistic</strong> All Rights Reserved.</p>

</div>

</footer>

<!-- CSS Scripts -->

<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js "

integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj "

crossorigin="anonymous "></script>

<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js "

integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo "

crossorigin="anonymous "></script>

<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js "

integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI "

crossorigin="anonymous "></script>

<script src='https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js'></script>

<script src='../side.js'></script>

</body>

</html>