C++ undefined reference to function error in g++ compiler only - c++

Question

I've looked at some of the other questions like this, but it seems like the functions should be all set up properly. Everything compiles correctly when run in CodeLite, but then compiling on a Linux server using g++, I get an undefined reference to function add_fraction, subtract_fraction, multiply_fraction, divide_fraction error in 'main.cpp' How can I fix this? Thanks!
main.cpp
#include <iostream>
#include <string>
#include "header.h"
using std::cout;
using std::cin;
using std::endl;
int main()
{
int numerator;
int denominator;
int numerator2;
int denominator2;
char operation;
cout << "Input the numerator: ";
cin >> numerator;
cout << "Input the denominator: ";
cin >> denominator;
cout << "Input the numerator2: ";
cin >> numerator2;
cout << "Input the denominator: ";
cin >> denominator2;
cout << "Input the operation: ";
cin >> operation;
if (operation != '+' || '-' || '*' || '/'){
cout << "Please input a valid operator: ";
cin >> operation;
}
if (operation == '+'){
Rational addFrac;
addFrac.add_fraction(numerator, numerator2, denominator, denominator2);
}
if (operation == '-'){
Rational subFrac;
subFrac.subtract_fraction(numerator, numerator2, denominator, denominator2);
}
if (operation == '*'){
Rational multFrac;
multFrac.multiply_fraction(numerator, numerator2, denominator, denominator2);
}
if (operation == '/'){
Rational divideFrac;
divideFrac.divide_fraction(numerator, numerator2, denominator, denominator2);
}
return 0;
}
header.h
#ifndef HEADER_H
#define HEADER_H
class Rational{
public:
void reduce_fraction(int &top, int &bottom);
void add_fraction(int numerator, int denominator, int numerator2, int denominator2);
void subtract_fraction(int numerator, int denominator, int numerator2, int denominator2);
void multiply_fraction(int numerator, int denominator, int numerator2, int denominator2);
void divide_fraction(int numerator, int denominator, int numerator2, int denominator2);
};
#endif // HEADER_H
header.cpp
#include "header.h"
#include <iostream>
#include <string>
using std::cout;
using std::cin;
using std::endl;
void Rational::reduce_fraction (int & top, int & bottom)
{
for (int i = top * bottom; i > 1; i--) {
if ((top % i == 0) && (bottom % i == 0)) {
bottom /= i;
top /= i;
}
}
}
void Rational::add_fraction (int numerator, int numerator2, int denominator, int denominator2)
{
int top;
int bottom;
top = numerator2 * denominator + denominator2 * numerator;
bottom = denominator2 * denominator;
cout << "Improper Fraction -> ";
cout << top << "/" << bottom << endl;
cout << "Simplified (Rational) Fraction -> ";
if (top == bottom){
cout << "1" << endl;
}
else {
Rational redu;
redu.reduce_fraction(top, bottom);
cout << top << "/" << bottom << endl;
}
}
void Rational::subtract_fraction (int numerator, int numerator2, int denominator, int denominator2)
{
int top;
int bottom;
top = denominator2 * numerator - denominator * numerator2;
bottom = denominator2 * denominator;
cout << "Improper Fraction -> ";
cout << top << "/" << bottom << endl;
cout << "Simplified (Rational) Fraction -> ";
if (top == bottom){
cout << "1" << endl;
}
else {
Rational redu;
redu.reduce_fraction(top, bottom);
cout << top << "/" << bottom << endl;
}
}
void Rational::multiply_fraction (int numerator, int numerator2, int denominator, int denominator2)
{
int top;
int bottom;
top = numerator * numerator2;
bottom = denominator * denominator2;
cout << "Improper Fraction -> ";
cout << top << "/" << bottom << endl;
cout << "Simplified (Rational) Fraction -> ";
if (top == bottom){
cout << "1" << endl;
}
else {
Rational redu;
redu.reduce_fraction(top, bottom);
cout << top << "/" << bottom << endl;
}
}
void Rational::divide_fraction (int numerator, int numerator2, int denominator, int denominator2)
{
int top;
int bottom;
top = denominator2 * numerator;
bottom = numerator2 * denominator;
cout << "Improper Fraction -> ";
cout << top << "/" << bottom << endl;
cout << "Simplified (Rational) Fraction -> ";
if (top == bottom){
cout << "1" << endl;
}
else {
Rational redu;
redu.reduce_fraction(top, bottom);
cout << top << "/" << bottom << endl;
}
}
Makefile
CXX = g++
CXXFLAGS = -g
default: main
search: main.cpp
${CXX} ${CXXFLAGS} main.cpp -o search
clean:
rm -f *.o main

Answer 1

You are not building header.cpp at all. It's not mentioned in your Makefile. You need to compile it and link it into your executable. Try this:
search: main.cpp header.cpp
${CXX} ${CXXFLAGS} main.cpp header.cpp -o search