27.5.2: C++ Examples
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Temperature
The temperature program main function is listed twice, once using if-then-else and once using switch, followed by the supporting functions.
If Then Else
// This program asks the user to select Fahrenheit or Celsius conversion // and input a given temperature. Then the program converts the given // temperature and displays the result. // // References: // https://www.mathsisfun.com/temperature-conversion.html // https://en.wikibooks.org/wiki/C%2B%2B_Programming #include using namespace std; char getChoice(); void processCelsius(); void processFahrenheit(); double getTemperature(string scale); double calculateCelsius(double fahrenheit); double calculateFahrenheit(double celsius); void displayResult(double temperature, string fromScale, double result, string toScale); int main() { char choice; choice = getChoice(); if (choice == 'C' || choice == 'c') { processCelsius(); } else if (choice == 'F' || choice == 'f') { processFahrenheit(); } else { cout << "You must enter C to convert to Celsius or F to convert to Fahrenheit." << endl; } return 0; }
Switch
int main() { char choice; choice = getChoice(); switch(choice) { case 'C': case 'c': processCelsius(); break; case 'F': case 'f': processFahrenheit(); break; default: cout << "You must enter C to convert to Celsius or F to convert to Fahrenheit." << endl; } return 0; }
Supporting Functions
char getChoice() { char choice; cout << "Enter C to convert to Celsius or F to convert to Fahrenheit:" << endl; cin >> choice; return choice; } void processCelsius() { double temperature; double result; temperature = getTemperature("Fahrenheit"); result = calculateCelsius(temperature); displayResult(temperature, "Fahrenheit", result, "Celsius"); } void processFahrenheit() { double temperature; double result; temperature = getTemperature("Celsius"); result = calculateFahrenheit(temperature); displayResult(temperature, "Celsius", result, "Fahrenheit"); } double getTemperature(string scale) { double temperature; cout << "Enter " << scale << " temperature:" << endl; cin >> temperature; return temperature; } double calculateCelsius(double fahrenheit) { double celsius; celsius = (fahrenheit - 32) * 5 / 9; return celsius; } double calculateFahrenheit(double celsius) { double fahrenheit; fahrenheit = celsius * 9 / 5 + 32; return fahrenheit; } void displayResult(double temperature, string fromScale, double result, string toScale) { cout << temperature << "° " << fromScale << " is " << result << "° " << toScale << endl; }
Output
Enter C to convert to Celsius or F to convert to Fahrenheit: c Enter Fahrenheit temperature: 100 100° Fahrenheit is 37.7778° Celsius Enter C to convert to Celsius or F to convert to Fahrenheit: f Enter Celsius temperature: 100 100° Celsius is 212° Fahrenheit Enter C to convert to Celsius or F to convert to Fahrenheit: x You must enter C to convert to Celsius or F to convert to Fahrenheit.
References
- Wikiversity: Computer Programming