F-Strings

Concepts: pyFStrings

Expressions in F-Strings You can put any expression inside the curly braces, not just variables: The expressions are evaluated, then the results are inserted into the string. Number Formatting F-strings support format specifications for controlling number display: F-strings have largely replaced concatenation as the preferred approach since Python 3.6. String Checking Methods Python provides methods to check string properties. These all return True or False. The username is alphanumeric (True), not all letters (False), not all digits (False). The PIN is all digits (True). Practical Validation These methods are perfect for input validation: This validates that a username is at least 3 characters, starts with a letter, and contains only letters and numbers. The second fails (too short), the