Question

Q1: What is the difference between function prototype and function definition in C++? Explain.

Q2: What does function prototype consist off and what does function definition consists of? (hint: components)

Q3: Do the names of parameters have to agree in the prototype, definition, and call to the function? Why or why not, explain?

Answer 1

1)

Function Prototype:

A function prototype is a declaration of a function: its name, parameters and return type. Unlike a full definition, the prototype terminates in a semi-colon and it doesn't has body.

 int myfunc(double param) ;

The actual names of the parameter values (param in above example) can be left out of the prototype. This gives the flexibility of renaming variables at will.

Function definition:

The function definition tells the compiler what task the function will be performing.  A function definition cannot be called unless the function is declared and it has body.  

int myfunc(double param){

return param

}

2)

Function Prototype consists of its name, parameters and return type.

Function definition consists of body and can return value to the caller.

3) no need , The actual names of the parameter values (param in above example) can be left out of the prototype. This gives the flexibility of renaming variables at will.

// Screenshot of the code

// Sample output

// Code to copy

#include<iostream>
using namespace std;
// function prototype
int myfunc(double p);
int main(){
   // calling function
   cout<< myfunc(25);
   return 0;
}
// function definition
int myfunc(double param) {
   return param*2;
}