bool¶print(f"type of True and False: {type(True)}") type of True and False: <class 'bool'>
print(f"0: {bool(0)}, 1: {bool(1)}") print(f"empty list: {bool([])}, list with values: {bool(['woop'])}") print(f"empty dict: {bool({})}, dict with values: {bool({'Python': 'cool'})}") 0: False, 1: True empty list: False, list with values: True empty dict: False, dict with values: True
==, !=, >, <, >=, <=¶print(f"{1 == 0}") print(f"{1 != 0}") print(f"{1 > 0}") print(f"{1 > 1}") print(f"{1 < 0}") print(f"{1 < 1}") print(f"{1 >= 0}") print(f"{1 >= 1}") print(f"{1 <= 0}") print(f"{1 <= 1}") False True True False False False True True False True
You can combine these:
print(f"{1 <= 2 <= 3}") True
and, or, not¶python_is_cool = True java_is_cool = False empty_list = [] secret_value = 3.14 print(f"Python and java are both cool: {python_is_cool and java_is_cool}") print(f"secret_value and python_is_cool: {secret_value and python_is_cool}") Python and java are both cool: False secret_value and python_is_cool: True
print(f"Python or java is cool: {python_is_cool or java_is_cool}") print(f"{1 >= 1.1 or 2 < 1.4}") Python or java is cool: True False
print(f"Java is not cool: {not java_is_cool}") Java is not cool: True
You can combine multiple statements, execution order is from left to right. You can control the execution order by using brackets.
print(bool(not java_is_cool or secret_value and python_is_cool or empty_list)) print(bool(not (java_is_cool or secret_value and python_is_cool or empty_list))) True False
if¶statement = True if statement: print("statement is True") if not statement: print("statement is not True") statement is True
empty_list = [] # With if and elif, conversion to `bool` is implicit if empty_list: print("empty list will not evaluate to True") # this won't be executed val = 3 if 0 <= val < 1 or val == 3: print("Value is positive and less than one or value is three") Value is positive and less than one or value is three
if-else¶my_dict = {} if my_dict: print("there is something in my dict") else: print("my dict is empty :(") my dict is empty :(
if-elif-else¶val = 88 if val >= 100: print("value is equal or greater than 100") elif val > 10: print("value is greater than 10 but less than 100") else: print("value is equal or less than 10") value is greater than 10 but less than 100
You can have as many elif statements as you need. In addition, else at the end is not mandatory.
greeting = "Hello fellow Pythonista!" language = "Italian" if language == "Swedish": greeting = "Hejsan!" elif language == "Finnish": greeting = "Latua perkele!" elif language == "Spanish": greeting = "Hola!" elif language == "German": greeting = "Guten Tag!" print(greeting) Hello fellow Pythonista!
For more detailed overview about conditionals, check this tutorial from Real Python.