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POWhat is the merit of the "function" type (not "pointer to function")
 

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  1. POWhat is the merit of the "function" type (not "pointer to function")
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    <p>Reading the C++ Standard, i see that there are "function" types and "pointer to function" types:</p> <pre><code>typedef int func(int); // function typedef int (*pfunc)(int); // pointer to function typedef func* pfunc; // same as above </code></pre> <p>I have never seen the function types used outside of examples (or maybe i didn't recognize their usage?). Some examples:</p> <pre><code>func increase, decrease; // declares two functions int increase(int), decrease(int); // same as above int increase(int x) {return x + 1;} // cannot use the typedef when defining functions int decrease(int x) {return x - 1;} // cannot use the typedef when defining functions struct mystruct { func add, subtract, multiply; // declares three member functions int member; }; int mystruct::add(int x) {return x + member;} // cannot use the typedef int mystruct::subtract(int x) {return x - member;} int main() { func k; // the syntax is correct but the variable k is useless! mystruct myobject; myobject.member = 4; cout &lt;&lt; increase(5) &lt;&lt; ' ' &lt;&lt; decrease(5) &lt;&lt; '\n'; // outputs 6 and 4 cout &lt;&lt; myobject.add(5) &lt;&lt; ' ' &lt;&lt; myobject.subtract(5) &lt;&lt; '\n'; // 9 and 1 } </code></pre> <p>Seeing that the function types support syntax that doesn't appear in C (declaring member functions), i guess they are not just a part of C baggage that C++ has to support for backward compatibility.</p> <p>So is there any use for function types, other than demonstrating some funky syntax?</p>
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