$ g++ --version
g++ (Homebrew GCC 9.2.0) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

#include <bits/stdc++.h>
using namespace std;

class Sample {

public:
    void init(int n) {
        printf("called init %d\n", n);
    }

    void up() {
        printf("called up\n");
    }
};

int main() {
    Sample s1;
    s1.init(100);
    s1.up();
}

called init 100
called up