make prototype of overloading function c++

Question

I want to make a overloading function with a prototype in C++.

#include <iostream>

using namespace std;

int rectangle(int p, int l);

int main() {
    cout << rectangle(3);
    return 0;
}

int rectangle(int p) {
    return p*p;
}

int rectangle(int p, int l) {
    return p*l;
}

---

I got error at

int rectangle(int p, int l);

is that possible make prototype with a overloading function? if possible how to do it

Answer 1

You've to declare the function before you use/call it. You did declare the 2 argument version of rectangle function but you seem to forget to declare the 1 argument taking version.

As shown below if you add the declaration for the 1 argument version then your program works(compiles).

#include <iostream>
using namespace std;

//declare the function before main
int rectangle(int p, int l);
int rectangle(int p);//ADDED THIS DECLARATION
int main() {
    cout << rectangle(3);
    return 0;
}
//define the functions after main
int rectangle(int p) {
    return p*p;
}
int rectangle(int p, int l) {
    return p*l;
}

The output of the program can be seen here.

Alternative solution:

If you don't want to declare each function separately then you should just define them before main instead of declaring them as shown below.

#include <iostream>
using namespace std;

//define the functions before main. This way there is no need to write a separate function declaration because all definition are declarations
int rectangle(int p) {
    return p*p;
}
int rectangle(int p, int l) {
    return p*l;
}

int main() {
    cout << rectangle(3);
    return 0;
}