Function power C++ - c++

Question

I need to write need a function to compute power in C++
I don't understand why my code below is wrong.
ex. : base: 2 exponent 3 -> result: 4.48498e-306
if i use "int" the result is -> 2
#include <iostream>
#include <cstdlib>
#include <cmath>
using namespace std;
double power(double base, double exponent);
int main()
{
double base, exponent, power;
cout << "Enter a base " << endl;
cin >> base;
cout << "Enter an exponent" << endl;
cin >> exponent;
cout << "The result is ': "<< power << endl;
return 0;
}
double power(double base, double exponent)
{
int i;
double s=1;
for (i = 0; i < exponent; ++i)
s *= base;
return s;
}
What am I doing wrong?

Answer 1

In your code you have two declarations of power.
double power(double base, double esponente);
double base,esponente,power;
You declare the variable power but you never initialize it before printing it, so it's going to be undefined. Rerunning your program will actually give you a different number, in all likelihood. You need to remove this local variable declaration, as it shadows the global function declaration.
Then, instead of
cout<<"\nL'elevamento a potenza e': "<<power<<endl;
You want this line:
cout<<"\nL'elevamento a potenza e': "<<power(base, esponente)<<endl;

Answer 2

You are either printing the address of the function power or printing the uninitialized value of the double power the way you have written the code. (Technically you are hitting an uninitialized shadowed variable). In any case, you are not even calling the function you wrote... How does the power function know to be called? With what arguments?
Fix 1. Suggest you delete the 'double' of power.
Fix 2. Actually call the function and use/store/print the result
example.
After getting input from user do this:
double result = power( base, exponent );
cout << result << endl;
To print the result.

Answer 3

You need call function like this, with parameters:
Here is your main. You don't need local variable power. You want call function with name power.
int main ()
{
double base,esponente;
cout<<" \n Inserisci base \n";
cin>>base;
cout<<"\nInserisci esponente\n";
cin>>esponente;
cout<<"\nL'elevamento a potenza e': "<<power(base,esponente)<<endl;
system ("PAUSE");
}