all()

Returns True if every item in an iterable evaluates to True, otherwise, it returns False.

Syntax

all(iterable)

Example 1

As long as one element in the iterable is False, all() will return False.

my_list = [True, "hello", 17]
print(all(my_list))
# Output: True
my_list = [False, "hello", 17]
print(all(my_list))
# Output: False

Example 2

If the iterable is empty, all() will return True.

my_list = []
print(all(my_list))
# Output: True

The integer 0 evaluates to False; however, all non-zero numbers and strings evaluate to True.

my_list = [4, 3, 2, 1, 0]
print(all(my_list))
# Output: False
my_list = [4, 3, 2, 1, "0"]
print(all(my_list))
# Output: True

Different Types of Iterables

all() can be used on any iterable, such as a list, set, string, dictionary, or tuple.

Lists

my_list = [1, 1, 0, True]
print(all(my_list))
# Output: False

This is False because the integer 0 is False.

Sets

my_set = {1, "False", True, 7}
print(all(my_set))
# Output: True

This is True because strings and non-zero integers are True.

Strings

my_string = "Python is more fun than Javascript"
print(all(my_string))
# Output: True

This is True because strings and non-zero integers are True.

Dictionaries

When all() is used with a dictionary, it evaluates the keys, not the values. That means, even if a value is False, all() will return True if all of the keys evaluate to True.

my_dict = {0: "zero", 1: "one", 2: "two"}
print(all(my_dict))
# Output: False

This is False because the first key, 0, is False.

Tuples

my_tuple = ("Heffalumps", "and", "Woozles")
print(all(my_tuple))
# Output: True

This is True because all items in the tuple are True.

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