Need to compare a temperature entered at the console? Input arrives as a string, so convert it with float() before comparing it with numbers. The result is a Python float even when the string contains an integer, as in float("-2") → -2.0. section 2.2.2
Compare a temperature and format the result
temperature = float(input("Temperature in Celsius: ")) if temperature < 10: label = "cold" elif temperature <= 25: label = "cool" else: label = "hot" print(f"You entered {temperature:.1f} degrees. It's {label}!") For input 15.75, the output is: You entered 15.8 degrees. It's cool! section 2.2.5
An f-string format specifier controls how a float appears in text: .2f displays two digits after the decimal point, .2e uses scientific notation, and .2% displays a percentage with two decimal places. Choose the form that makes the value easiest to read. section 2.1.4
decimal_number = 1.23456
print(f"Two digits: {decimal_number:.2f}")
# output: Two digits: 1.23
print(f"Four digits: {decimal_number:.4f}")
# output: Four digits: 1.2346
Compare .2f and .4f on the same value to see how the requested number of displayed decimal places changes the output. section 2.1.4
Conversion can fail: float("3.5a") raises ValueError. Use try...except... when input may be invalid. When exchanging data through JSON, remember that JSON has one number category, while Python represents corresponding values with int or float. section 2.2.2 section 9.3.2
