# Applied Programming/Functions/Python3

## functions.py

```"""This program converts a Fahrenheit temperature to Celsius.

Input:
Fahrenheit temperature

Output:
Fahrenheit temperature
Celsius temperature

Example:
Enter Fahrenheit temperature:
100
100.0° Fahrenheit is 37.8° Celsius

References:
* http://www.mathsisfun.com/temperature-conversion.html

"""

def get_fahrenheit():
"""Gets Fahrenheit temperature.

Args: None

Returns:
float: Fahrenheit temperature

"""
print("Enter Fahrenheit temperature:")
fahrenheit = float(input())
return fahrenheit

def fahrenheit_to_celsius(fahrenheit):
"""Converts Fahrenheit temperature to Celsius.

Args:
fahrenheit (float): Fahrenheit temperature to be converted

Returns:
float: Celsius temperature

"""
TEMPERATURE_DIFFERENCE = 32
TEMPERATURE_RATIO = 5 / 9
celsius = (fahrenheit - TEMPERATURE_DIFFERENCE) * TEMPERATURE_RATIO
return celsius

def display_results(fahrenheit, celsius):
"""Displays Fahrenheit and Celsius temperatures.

Args:
fahrenheit (float): Fahrenheit temperature
celsuis (float): Celsius temperature

Returns: None

"""
print(f'{fahrenheit:.1f}° Fahrenheit is {celsius:.1f}° Celsius')

def main():
"""Runs the main program logic."""

fahrenheit = get_fahrenheit()
celsius = fahrenheit_to_celsius(fahrenheit)
display_results(fahrenheit, celsius)

main()
```

## Try It

Copy and paste the code above into one of the following free online development environments or use your own Python3 compiler / interpreter / IDE.