Temperature conversion is a fundamental programming exercise that teaches essential C programming concepts. In this tutorial, we’ll build a comprehensive temperature converter that handles Celsius, Fahrenheit, and Kelvin conversions with proper input validation and user-friendly interface.
Learning Objectives
- Understanding mathematical operations in C
- Working with floating-point arithmetic
- Implementing menu-driven programs
- Input validation and error handling
- Creating reusable functions
Basic Temperature Converter
#include <stdio.h>
int main() {
float celsius, fahrenheit, kelvin;
int choice;
printf("==========================================\n");
printf(" TEMPERATURE CONVERTER PROGRAM \n");
printf("==========================================\n\n");
printf("Select conversion type:\n");
printf("1. Celsius to Fahrenheit\n");
printf("2. Fahrenheit to Celsius\n");
printf("3. Celsius to Kelvin\n");
printf("4. Kelvin to Celsius\n");
printf("5. Fahrenheit to Kelvin\n");
printf("6. Kelvin to Fahrenheit\n");
printf("Enter your choice (1-6): ");
scanf("%d", &choice);
switch(choice) {
case 1:
printf("Enter temperature in Celsius: ");
scanf("%f", &celsius);
fahrenheit = (celsius * 9.0/5.0) + 32;
printf("%.2f°C = %.2f°F\n", celsius, fahrenheit);
break;
case 2:
printf("Enter temperature in Fahrenheit: ");
scanf("%f", &fahrenheit);
celsius = (fahrenheit - 32) * 5.0/9.0;
printf("%.2f°F = %.2f°C\n", fahrenheit, celsius);
break;
case 3:
printf("Enter temperature in Celsius: ");
scanf("%f", &celsius);
kelvin = celsius + 273.15;
printf("%.2f°C = %.2fK\n", celsius, kelvin);
break;
case 4:
printf("Enter temperature in Kelvin: ");
scanf("%f", &kelvin);
if (kelvin < 0) {
printf("Error: Temperature cannot be below absolute zero!\n");
} else {
celsius = kelvin - 273.15;
printf("%.2fK = %.2f°C\n", kelvin, celsius);
}
break;
case 5:
printf("Enter temperature in Fahrenheit: ");
scanf("%f", &fahrenheit);
kelvin = (fahrenheit - 32) * 5.0/9.0 + 273.15;
printf("%.2f°F = %.2fK\n", fahrenheit, kelvin);
break;
case 6:
printf("Enter temperature in Kelvin: ");
scanf("%f", &kelvin);
if (kelvin < 0) {
printf("Error: Temperature cannot be below absolute zero!\n");
} else {
fahrenheit = (kelvin - 273.15) * 9.0/5.0 + 32;
printf("%.2fK = %.2f°F\n", kelvin, fahrenheit);
}
break;
default:
printf("Invalid choice! Please run the program again.\n");
break;
}
return 0;
}Advanced Temperature Converter with Functions
#include <stdio.h>
#include <stdlib.h>
// Function prototypes
float celsiusToFahrenheit(float celsius);
float fahrenheitToCelsius(float fahrenheit);
float celsiusToKelvin(float celsius);
float kelvinToCelsius(float kelvin);
float fahrenheitToKelvin(float fahrenheit);
float kelvinToFahrenheit(float kelvin);
void displayMenu();
int validateKelvin(float kelvin);
int main() {
float temperature;
int choice;
char continueChoice;
do {
printf("==========================================\n");
printf(" ADVANCED TEMPERATURE CONVERTER \n");
printf("==========================================\n\n");
displayMenu();
printf("Enter your choice (1-7): ");
scanf("%d", &choice);
if (choice == 7) {
printf("Thank you for using Temperature Converter!\n");
break;
}
if (choice < 1 || choice > 7) {
printf("Invalid choice! Please try again.\n");
continue;
}
switch(choice) {
case 1:
printf("Enter temperature in Celsius: ");
scanf("%f", &temperature);
printf("%.2f°C = %.2f°F\n", temperature, celsiusToFahrenheit(temperature));
break;
case 2:
printf("Enter temperature in Fahrenheit: ");
scanf("%f", &temperature);
printf("%.2f°F = %.2f°C\n", temperature, fahrenheitToCelsius(temperature));
break;
case 3:
printf("Enter temperature in Celsius: ");
scanf("%f", &temperature);
printf("%.2f°C = %.2fK\n", temperature, celsiusToKelvin(temperature));
break;
case 4:
printf("Enter temperature in Kelvin: ");
scanf("%f", &temperature);
if (validateKelvin(temperature)) {
printf("%.2fK = %.2f°C\n", temperature, kelvinToCelsius(temperature));
} else {
printf("Error: Temperature cannot be below absolute zero (0K)!\n");
}
break;
case 5:
printf("Enter temperature in Fahrenheit: ");
scanf("%f", &temperature);
printf("%.2f°F = %.2fK\n", temperature, fahrenheitToKelvin(temperature));
break;
case 6:
printf("Enter temperature in Kelvin: ");
scanf("%f", &temperature);
if (validateKelvin(temperature)) {
printf("%.2fK = %.2f°F\n", temperature, kelvinToFahrenheit(temperature));
} else {
printf("Error: Temperature cannot be below absolute zero (0K)!\n");
}
break;
}
printf("\nWould you like to perform another conversion? (y/n): ");
scanf(" %c", &continueChoice);
} while (continueChoice == 'y' || continueChoice == 'Y');
printf("Goodbye!\n");
return 0;
}
void displayMenu() {
printf("Select conversion type:\n");
printf("1. Celsius to Fahrenheit\n");
printf("2. Fahrenheit to Celsius\n");
printf("3. Celsius to Kelvin\n");
printf("4. Kelvin to Celsius\n");
printf("5. Fahrenheit to Kelvin\n");
printf("6. Kelvin to Fahrenheit\n");
printf("7. Exit\n\n");
}
float celsiusToFahrenheit(float celsius) {
return (celsius * 9.0/5.0) + 32;
}
float fahrenheitToCelsius(float fahrenheit) {
return (fahrenheit - 32) * 5.0/9.0;
}
float celsiusToKelvin(float celsius) {
return celsius + 273.15;
}
float kelvinToCelsius(float kelvin) {
return kelvin - 273.15;
}
float fahrenheitToKelvin(float fahrenheit) {
return fahrenheitToCelsius(fahrenheit) + 273.15;
}
float kelvinToFahrenheit(float kelvin) {
return celsiusToFahrenheit(kelvinToCelsius(kelvin));
}
int validateKelvin(float kelvin) {
return kelvin >= 0;
}Temperature Conversion Formulas
Celsius to Fahrenheit: F = (C × 9/5) + 32
Fahrenheit to Celsius: C = (F – 32) × 5/9
Celsius to Kelvin: K = C + 273.15
Kelvin to Celsius: C = K – 273.15
Fahrenheit to Kelvin: K = (F – 32) × 5/9 + 273.15
Kelvin to Fahrenheit: F = (K – 273.15) × 9/5 + 32
Key Programming Concepts
Function Design: Each conversion is implemented as a separate function, promoting code reusability and modularity.
Input Validation: The program validates temperature values against absolute zero limits for each scale.
Menu Systems: Interactive menu-driven interface with multiple operation modes.
Error Handling: Comprehensive error checking for invalid inputs and impossible temperature values.
Compilation and Execution
# Compile the program
gcc temperature_converter.c -o temp_converter
# Run the program
./temp_converterPractice Exercises
- Add Rankine temperature scale conversion
- Create a batch conversion feature for multiple temperatures
- Add historical temperature data comparison
- Implement temperature range validation for different scales
- Create a file output feature to save conversion results
Conclusion
This temperature converter demonstrates fundamental C programming concepts including mathematical operations, function design, and input validation. The modular approach makes the code maintainable and extensible for future enhancements.
