Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://realpython.com/ref/builtin-exceptions/valueerror/ below:

Python’s Built-in Exceptions – Real Python

1. Reference
2. Python’s Built-in Exceptions/

ValueError is a built-in exception that gets raised when a function or operation receives an argument with the right type but an invalid value. It means the argument’s type is okay, but its actual value isn’t acceptable for the operation at hand.

You can handle ValueError to gracefully deal with invalid input, so your program doesn’t crash unexpectedly and can give your users helpful feedback.

• Calling a function with an argument that has the right type but an inappropriate value
• Converting strings to numbers and the string doesn’t represent a valid number

• Validating function arguments to ensure they’re in acceptable ranges or sets
• Handling user input that needs specific formatting or value constraints
• Enforcing value restrictions in custom data types or classes

Here’s an example where Python raises a ValueError when you try converting a string that doesn’t represent a valid number into an integer:

>>> int("one")
Traceback (most recent call last):
    ...
ValueError: invalid literal for int() with base 10: 'one'

You can handle ValueError with a try … except block to show a user-friendly message or choose an alternative action:

>>> user_input = "one"
>>> try:
...     number = int(user_input)
... except ValueError:
...     print(f"Could not convert '{user_input}' to an integer.")
...
Could not convert 'one' to an integer.

If you’re writing a function that demands certain value constraints, you can raise ValueError to enforce them:

>>> def set_age(age):
...     if age < 0:
...         raise ValueError("Age can't be negative")
...     print(f"Age is {age} years")

>>> set_age(-5)
Traceback (most recent call last):
    ...
ValueError: Age can't be negative

For additional information on related topics, take a look at the following resources:

• Python's raise: Effectively Raising Exceptions in Your Code (Tutorial)
• Strings and Character Data in Python (Tutorial)
• Numbers in Python (Tutorial)
• Working With Python's Built-in Exceptions (Course)
• Python's Built-in Exceptions: A Walkthrough With Examples (Quiz)
• Using raise for Effective Exceptions (Course)
• Python's raise: Effectively Raising Exceptions in Your Code (Quiz)
• Strings and Character Data in Python (Course)
• Python Strings and Character Data (Quiz)

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4