How to Access Friend Functions Defined in a Class in C ?

Access Friend Functions Defined in Class

In C , friend functions are declared within classes but can access private and protected members of the class. Consider the following code snippet:

<code class="cpp">class A {
    friend void fun(A a);
    friend void fun2();
    friend void fun3();
};

void fun3() {
    std::cout <p>Accessing the fun(A) function works fine as it has a parameter of type A, allowing Argument-Dependent Lookup to locate it. However, there is an issue with accessing the global functions fun2() and fun3().</p>
<p>The declaration of fun2 within the class makes it a friend function but does not declare it in the global scope. Consequently, when accessing fun2() outside the class:</p>
<ul>
<li>fun2(); results in an error.</li>
<li>A::fun2(); also results in an error.</li>
</ul>
<p>To resolve this, the correct approach is to define all friend functions outside the class and make them explicit friends of the class:</p>
<pre class="brush:php;toolbar:false"><code class="cpp">class A {
    friend void fun(A a);
    friend void fun2();
    friend void fun3();
};

void fun(A a) { std::cout <p>Defining friend functions this way allows them to be accessed both inside and outside the class.</p></code>

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