//test.h
#ifndef test_h
#define test_h

void fun1();

void fun2();
#endif

//test.cpp
#include <stdio.h>
#include <iostream>
#include "test.h"

void fun1(){
    std::cout << "text1";
}
void fun2(){
    std::cout << "text2";
}

//main.cpp
#include <iostream>
#include "test.h"

using namespace std;

int main(int argc, const char * argv[]) {
        cout << "Hello, World!\n";
    fun1();
    fun2();
    return 0;
}