03. Expressions and Boolean Logic Free Online FlashCards

What is an expression in Python?

An expression is code evaluated to produce a value; it may contain literals, variables, operators, and function calls.

In `a + b`, what are the operator and operands?

The operator performs the operation, while the operands are the values on which it operates. In `a + b`, `+` is the operator and `a` and `b` are operands.

What is the result of `7 // 2`?

`7 // 2` evaluates to `3` because floor division returns the floor of the quotient.

What does `7 % 2` evaluate to?

`7 % 2` evaluates to `1`; the `%` operator returns the remainder after division.

How do `=` and `==` differ in Python?

`=` assigns a value, while `==` tests whether two values are equal. For example, `x = 10` assigns; `x == 10` compares.

What does `10 <= score <= 20` mean?

The chained comparison is equivalent to `10 <= score and score <= 20`. It checks that `score` lies from 10 through 20, inclusive.

What do Python's `not`, `and`, and `or` operators do?

`not` reverses a truth value, `and` is true when both conditions are true, and `or` is true when at least one condition is true.

Which common Python values are false in a Boolean context?

`False`, `None`, numeric zero, and empty strings and containers are false in Boolean contexts; most other values are true.

When do `and` and `or` short-circuit?

`A and B` stops when `A` is false, while `A or B` stops when `A` is true, because the final result is already determined.

What can Python's `and` and `or` return?

Python's `and` and `or` return one of their operands, not necessarily `True` or `False`. Thus, `entered_name or "Guest"` produces `"Guest"` when `entered_name` is empty.

How does `+` combine strings in Python?

The `+` operator concatenates strings, and both operands must be strings. Convert other types with `str()` or use a formatted string.

What is the result of `"-" * 5`?

`"-" * 5` evaluates to `"-----"`; multiplying a string repeats it the specified number of times.