C++ my code compiles but the main function won't call the other functions

This is suppose to take a value for feet and inches, and convert to metric producing a number in metres and centimetres. The code compiles in Bloodshed but only executes the main function.

#include <iostream>

using namespace std;
int cal();
int output();

int cal(double f, double fD, double m, double i)//, double c)
{
    fD = i / 12;
    f = f + fD;
    m = f * 0.3048;
    //c = m - static_cast<int>(m);
    return (m);

}

int output(double m)//, double c)
{
    //int cal(double f,double fD, double ,double i, double c);
    cout << "The value in metres is " << m;
    //cout << "\nThe value of centimetres is " << c;
}

int main()
{
    double feet, inches;
    double fDec, metres;//, centi;

    cout << "What is your value of feet?\n";
    cin >> feet;
    cout << "What is the value of inches?\n";
    cin >> inches;

    int cal(double feet, double fDec, double metres, double inches);//, double centi);  
    int output(double metres);//, double centi);
    return 0;
}