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What are the two main purposes of the 'assert' statement in Python?

Susan Sarandon
Susan SarandonOriginal
2024-11-14 21:04:02344browse

What are the two main purposes of the

Understanding the Purpose of "assert" in Python

The "assert" statement is a valuable tool in Python and other programming languages. It serves two primary purposes:

  1. Early Detection of Errors:
    "assert" helps identify problems in your program at an early stage, before they escalate into complex issues. For example, it can detect a type error immediately, preventing it from propagating further.
  2. Documentation and Clarity:
    Assert statements act as inline documentation, conveying to other developers that a specific condition is true and should not be broken. By asserting that a particular state is expected, you make the code more readable and self-explanatory.

To use "assert," simply follow this syntax:

assert condition

If the "condition" is true, the program continues execution. However, if the condition is false, an "AssertionError" is raised.

In Python, "assert" is similar to the following code:

if not condition:
    raise AssertionError()

Example:

>>> assert True  # No action performed
>>> assert False
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AssertionError

Optional Message:

You can include an optional message to be printed if the assertion fails:

assert False, "Oh no! This assertion failed!"

Note:

  • Avoid using parentheses to call assert like a function. It is a statement, not a function.
  • Assertions can be disabled by running Python in optimized mode (-O flag), where debug is set to False.

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