I can't get it to display the updated temperature - c++

Question

I'm trying to make it so that if the user chooses 1, it should increase the temp by 5, and decrease if the user chooses 2. the problem I'm having is that it doesn't update the value of the temperature.
UPDATE: I've finally got the math part to work but for some reason when i print the value of temperature it doesn't save the updates. If i do warmer, it's always at 20 and if i do cooler it's always at 10. I'm guessing i have to use the getTemp() because im only editing the local variable? How do I go about this?
#include <iostream>
using namespace std;
class heater
{
public:
int temperature;
int min;
int max;
int increment;
heater(int min=0, int max=60)
{
increment = 5;
temperature = 15;
}
int warmer(int);
int cooler(int);
int getTemp(int);
};
int heater::warmer(int temperature) {
if (temperature > (temperature - increment))
{
temperature += increment;
return temperature;
}
else cout << "Max temp reached.";
}
int heater::cooler(int temperature) {
if (temperature < (temperature + increment)){
temperature -= increment;
return temperature;
}
else cout << "Min temp reached.";
}
int heater::getTemp(int temperature) {
return temperature;
}
int main()
{
heater w;
heater c;
heater t;
heater g;
int i;
int number;
int temp;
for (i = 1; i != 0; i=1)
{
cout << "\n1. Warmer \n";
cout << "2. Cooler \n";
cout << "Press 0 to exit. \n";
cin >> number;
if (number == 1) {
temp = w.warmer(t.temperature);
cout << "The temperature is now: " << temp;
}
else if (number == 2) {
temp = c.cooler(t.temperature);
cout << "The temperature is now: " << temp;
}
else if (number == 0){
break;
}
}
return 0;
}

Answer 1

In int heater::warmer(int temperature) parameter named temperature shadows class member called temperature and you only modify that local parameter.
Simply remove that parameters and modify your class member:
#include <iostream>
using namespace std;
class heater
{
public:
int temperature;
heater()
{
temperature = 15;
}
int warmer();
int cooler();
int getTemp();
};
int heater::warmer() {
temperature -= 5;
}
int heater::cooler() {
temperature += 5;
}
int heater::getTemp() {
return temperature;
}
int main()
{
heater w;
heater c;
heater t;
int number;
cout << "1. Warmer \n";
cout << "2. Cooler \n";
cin >> number;
if (number == 1) {
w.warmer();
cout << "The temperature is now: " << t.temperature;
}
else if (number == 2) {
c.cooler();
cout << "The temperature is now: " << t.temperature;
}
return 0;
}
Also, the line heater getTemp(); doesn't do anything useful. It declares a global function that returns heater and takes no parameters. You probably wanted to call the member function like this:
cout << "The temperature is now: " << t.getTemp();