1. If else statements

  • if

if True:
    print('True value')

Upper code is returning following text:

True value

if False:
    print('False value')

As you there is nothing printed.

1.1. Conversion of list into boolean

empty_list = []

if empty_list:
    print('List with content')
else:
    print('List empty')

Text above is returning following text:

List empty

Attention

What happened here is implicit conversion of type list into bool

>>> bool([])
False

>>> bool([1, 2, 3])
True

1.2. Checking bool values

>>> bool(-1)
True

>>> bool(0)
False

>>> bool(124)
True

>>> bool({})
False

Warning

Every number but not zero will return True. Number -1 if written in binary (U2) got got ones (1) on decimal positions

1.3. Checking ranges

temperature = 18

if 16 <= temperature < 24:
    print('Temperature good for biking')
else:
    print('Temperature not appropiate for biking')

This will give us

Temperature good for biking

If we change temperature to below zero

temperature = -3

if 16 <= temperature < 24:
    print('Temperature good for biking')
elif 3 <= temperature < 16:
    print('Temperature good for walk')
elif -5 <= temperature < 3:
    print('Temperature good for skiing')
else:
    print('Don`t know what to do :(')

Temperature good for skiing

1.4. Exercises - part 1

  1. Let user put his age, check if he is adult,

  2. Let user put number, check if the value is float or integer

Hint

There are many ways to do that. Find your own ;)

1.4.1. Exercises - part 2

  1. Create simple BMI calculator, which will get all values from input. In result it should return status if person is:

    • Overweight,

    • Normal,

    • Underweight

1.4.2. Exercises - part 3

  • Use library os function system for checking if host is active

    • Depending on a status print proper message,

Hint

Bear in mind that systems got own status codes after execution commands