Python - all() function

Last Updated : 1 Oct, 2026

The all() function in Python is a built-in function used to check whether all elements in an iterable evaluate to True. It returns True when every element is truthy or when the iterable is empty; otherwise, it returns False.

Example:

Python 
values = [True, True, False]

result = all(values)

print(result)

Output
False

Explanation:

  • The list contains three True values.
  • Since all elements evaluate to True, all() returns True.

Syntax

all ( iterable )

Explanation:

  • iterable is any iterable object such as a list, tuple, set, string, dictionary, or generator.
  • Returns True if all elements evaluate to True.
  • Returns False when any element evaluates to False.

With Strings

A string is an iterable, so all() check each character.

Python 
text = "Python"

print(all(text))

Output
True

Explanation:

  • Each character is a non-empty string.
  • Non-empty strings evaluate to True.
  • Therefore, all() returns True.

With Conditions

A common use of all() is checking whether every element satisfies a condition.

Example 1:

Python 
numbers = [10, 20, 30, 40]

result = all(num > 5 for num in numbers)

print(result)

Output
True

Explanation:

  • Expression checks whether each number is greater than 5.
  • Every number satisfies the condition.
  • Hence, all() returns True.

Example 2:

Python 
numbers = [10, 20, 3, 40]

result = all(num > 5 for num in numbers)

print(result)

Output
False

Explanation:

  • 10 and 20 are greater than 5.
  • 3 is not greater than 5.
  • Therefore, all() returns False.

With Empty Iterable

When an empty iterable is passed to all(), it returns True.

Python 
values = []

print(all(values))

Output
True

Explanation:

  • There is no element that evaluates to False.
  • Therefore, all() returns True for an empty iterable.

With Dictionary

When a dictionary is passed directly to all(), its keys are evaluated.

Example 1:

Python 
data = {
    1: "Python",
    2: "Java",
    3: "C++"
}

print(all(data))

Output
True

Explanation:

  • all(data) iterates over the dictionary keys.
  • Keys 1, 2, and 3 are all truthy.
  • Therefore, the result is True.

Example 2:

Python 
data = {
    0: "Python",
    2: "Java"
}

print(all(data))

Output
False

Explanation:

  • Dictionary iteration checks the keys.
  • 0 is a falsy value.
  • Therefore, all() returns False.

Short-Circuiting in all()

all() function uses short-circuit evaluation. It stops checking elements as soon as a falsy value is found.

Python 
def check(value):
    print("Checking:", value)
    return value

result = all(check(x) for x in [1, 2, 0, 4])

print("Result:", result)

Output
Checking: 1
Checking: 2
Checking: 0
Result: False

Explanation:

  • all() checks 1 and 2.
  • 0 evaluates to False.
  • all() immediately stops execution.
  • 4 is not checked.

With Generator Expression

Generator expressions can be used with all() to check conditions without first creating a separate list.

Python 
numbers = range(1, 6)

result = all(num % 2 == 0 for num in numbers)

print(result)

Output
False

Explanation:

  • The expression checks whether each number is even.
  • 1 is not even.
  • all() immediately returns False.

Practical Example

Checking Weather a List is Sorted

Python 
numbers = [1, 2, 3, 4, 5]

result = all(
    numbers[i] <= numbers[i + 1]
    for i in range(len(numbers) - 1)
)

print(result)

Output
True

Explanation:

  • Each element is compared with the next element.
  • Every element is less than or equal to the following element.
  • Therefore, the list is sorted in ascending order.
  • all() returns True.
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