Undefined reference to 'print(int)' [Linker error]

Assignment says: Write a program that consists of two source-files. The first (Main.c) contains the main() function and gives the variable i a value. The second source-file (Print.c) multiplies i by 2 and prints it. Print.c contains the function print() which can be called from main().

In my attempt to do this assignment, I created three files: main.cpp

#include <stdio.h>
#include "print.h"
using namespace std;

// Ex 1-5-3

// Global variable
int i = 2;


int main() {
    print(i);

    return 0;
}

print.cpp:

#include <stdio.h>
#include "print.h"
using namespace std;

// Ex 1-5-3

// Fetch global variable from main.cpp
extern int i;

void print(int i) {
    printf("%d", 2*i);
}

print.h:

#ifndef GLOBAL_H // head guards
#define GLOBAL_H

void print(int i);

#endif

I compiled print.cpp and when I tried to compile and run main.cpp, it says: [Linker error] undefined reference to 'print(int)'

Why isn't it accepting my definition of void print (int i) in print.cpp and referring to it through the header print.h? Thanks!