Python assert Keyword

By IncludeHelp Last updated : December 07, 2024

Description and Usage

The assert is a keyword (case-sensitive) in python, it is used to debug the code. Generally, it can be used to test a condition – if a condition returns False – it returns an Assertion Error (AssertionError).

Syntax

Syntax of assert keyword:

assert statement

Sample Input/Output

Input:
num = 10

# assert statement
assert num==20

Output:
assert num==20
AssertionError

Example 1

Test a False result

# python code to demonstrate example of 
# assert statement 

num = 10    # number

# assert statements

# nothing will happed as the condition is true
assert num==10

#AssertionError will generate as the condition is false
assert num==20

Output

Traceback (most recent call last):
  File "/home/main.py", line 12, in <module>
    assert num==20
AssertionError

Example 2

Test a False result and return a customize message

# python code to demonstrate example of 
# assert statement 

num = 10    # number

# assert statements

# nothing will happed as the condition is true
assert num==10

#AssertionError will generate as the condition is false
assert num==20, "There is an error with num's value"

Output

Traceback (most recent call last):
  File "/home/main.py", line 12, in <module>
    assert num==20, "There is an error with num's value"
AssertionError: There is an error with num's value

Python with Keyword

Python else Keyword

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