/* fooclass.h: */

class Fooclass {
    void foo();
};

/* fooclass.cpp: */

#include "fooclass.h"

void Fooclass::foo() {
    //code
}

/* main.cpp: */

#include "fooclass.h"

int main() {
    Fooclass test;
    test.foo();
    
    return 0;
}