#import <iostream>
#import <cmath>

#define COLUMN_SEPARATOR "t| "
#define MAX_TEMP 500
#define MIN_TEMP -500

inline bool between(double x, double max, double min) {
    return max >= x && min <= x;
}

void getInput(double &lower, double &upper, double &step) {
    double temp1, temp2;
    std::cout << "Please enter consecutively the upper and lower limits, both between " <<  MIN_TEMP << " and " << MAX_TEMP << "." << std::endl;
    std::cin >> temp1;
    std::cin >> temp2;
    while (!between(temp1, MAX_TEMP, MIN_TEMP) || !between(temp2, MAX_TEMP, MIN_TEMP)) {
        std::cout << "At least one of the temperatures is out of bounds. Please reenter:" << std::endl;
        std::cin >> temp1;
        std::cin >> temp2;
    }
    upper = std::max(temp1, temp2);
    lower = std::min(temp1, temp2);
    std::cout << "Please enter a positive stepsize, smaller than the difference between the limits." << std::endl;
    std::cin >> step;
    while (step < 0 || step > upper - lower) {
        std::cout << "The stepsize is out of bounds. Please reenter:" << std::endl;
        std::cin >> step;
    }
}

double toFahrenheit(double celsius) {
    return celsius*(9/5) + 32;
}

void printTable(double start, double end, double step) {
    std::cout << "Celsius" << COLUMN_SEPARATOR << "Fahrenheit" << std::endl;
    std::cout << "=======" << COLUMN_SEPARATOR << "==========" << std::endl;
    for (double i = start; i < end; i += step) {
        std::cout << i << COLUMN_SEPARATOR << toFahrenheit(i) << std::endl;
    }
}

int main() {
    double start, end, step;
    getInput(start, end, step);
    printTable(start, end, step);
    return 0;
}

192:Challenges 11684$ ./a.out Please enter consecutively the upper and lower limits, both between -500 and 500.
3.692
65.937
Please enter a positive stepsize, smaller than the difference between the upper and lower limit.
5.3729
Celsius | Fahrenheit
======= | ==========
3.692   | 35.692
9.0649  | 41.0649
14.4378 | 46.4378
19.8107 | 51.8107
25.1836 | 57.1836
30.5565 | 62.5565
35.9294 | 67.9294
41.3023 | 73.3023
46.6752 | 78.6752
52.0481 | 84.0481
57.421  | 89.421
62.7939 | 94.7939