C++

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Function Prototype

A function's declaration must precede any instance of it. In case the declaration of a function is placed after a call to the function itself, a prototype can be used to make the compiler aware of the function's existence. Given the function:

void aFunction()
{
     cout << "Hello.";
}

its prototype is:

void aFunction();

Example


#include <iostream>
using namespace std;

void aFunction(); // function prototype

int main()
{
     aFunction();  // function call
}

void aFunction()  // function declaration
{
     cout << "Hello.";
}

Output

Hello.