2 Variables and Data Types Free Online FlashCards

What does dynamically typed mean in Python?

Python is dynamically typed: a name has no permanently declared type and may later refer to a value of a different type.

What rules apply to Python names?

A Python name may contain letters, digits, and underscores, but it cannot begin with a digit. Names are case-sensitive, and keywords cannot be ordinary names.

How do `=` and `==` differ?

The operator `=` assigns or binds a value to a name; it does not test mathematical equality. The comparison operator `==` tests whether two values are equal.

What happens when a name is rebound?

Assignment can rebind a name. After `temperature = 18` followed by `temperature = 21`, the name `temperature` refers to `21`.

Why can `x, y = y, x` swap values?

In `x, y = y, x`, Python evaluates the right-hand side before assignments take effect, so the two values are swapped without a temporary variable.

How can you inspect an object's type?

The `type()` function inspects an object and reports its type, such as `int`, `float`, `str`, or `bool`.

What do `/`, `//`, `%`, and `**` do?

`/` performs ordinary division, `//` performs floor division, `%` returns the remainder, and `**` raises a value to a power.

What type does `input()` return?

`input()` returns a string. Convert it before numeric operations, such as with `age = int(input("Enter your age: "))`.

How does `int()` convert a float?

Converting a float to `int` discards the fractional part rather than rounding: `int(7.9)` is `7` and `int(-7.9)` is `-7`.

What does string immutability mean?

Strings are immutable Unicode sequences, so their contents cannot be changed in place. Create a new string instead, such as by concatenating text.

How does Python index strings?

Python strings use zero-based indexing: `word[0]` returns the first character. Negative indexing counts from the end, so `word[-1]` returns the last character.

What is an f-string used for?

An f-string inserts expressions directly into text, as in `f"You ordered {quantity} {item}s."`. It provides readable formatted output.