Python all()

The all() method returns True when all elements in the given iterable are true. If not, it returns False.

The syntax of all() method is:

all(iterable)

all() Parameters

The all() method takes a single parameter:

Return Value from all()

The all() method returns:

  • True - If all elements in an iterable are true
  • False - If any element in an iterable is false
Truth table for all()
When Return Value
All values are true True
All values are false False
One value is true (others are false) False
One value is false (others are true) False
Empty Iterable True

Example 1: How all() works for lists?

# all values true
l = [1, 3, 4, 5]
print(all(l))

# all values false
l = [0, False]
print(all(l))

# one false value
l = [1, 3, 4, 0]
print(all(l))

# one true value
l = [0, False, 5]
print(all(l))

# empty iterable
l = []
print(all(l))

When you run the program, the output will be:

True
False
False
False
True

The any() method works in similar way for tuples and sets like lists.

Example 2: How all() works for strings?

s = "This is good"
print(all(s))

# 0 is False
# '0' is True
s = '000'
print(all(s))

s = ''
print(all(s))

When you run the program, the output will be:

True
True
True

Example 3: How all() works with Python dictionaries?

In case of dictionaries, if all keys (not values) are true or the dictionary is empty, all() returns True. Else, it returns false for all other cases..

s = {0: 'False', 1: 'False'}
print(all(s))

s = {1: 'True', 2: 'True'}
print(all(s))

s = {1: 'True', False: 0}
print(all(s))

s = {}
print(all(s))

# 0 is False
# '0' is True
s = {'0': 'True'}
print(all(s))

When you run the program, the output will be:

False
True
False
True
True