ATBSWP Ch. 1

Why is eggs a valid variable name while 100 is invalid?

Variable names cannot begin with a number.

Which of the following is a variable, and which is a string? spam 'spam'

Variable: spam String: 'spam' Strings always start and end with quotes

This chapter introduced assignment statements, like spam = 10. What is the difference between an expression and a statement?

An expression evaluates to a single value. A statement does not.

What is an expression made up of? What do all expressions do?

An expression is a combination of values and operators. All expressions evaluate (that is, reduce) to a single value.

What should the following two expressions evaluate to? 'spam' + 'spamspam' 'spam' * 3

Both expressions evaluate to the string 'spamspamspam'

Name 3 data types

Integers, floating-point numbers, and strings.

Which of the following are operators, and which are values? * 'hello' -88.8 - / + 5

Operators: +, -, *, / Values: 'hello', -88.5, 5

What does the variable bacon contain after the following code runs? bacon = 20 bacon + 1

The bacon variable is set to 20. The bacon + 1 expression does not reassign the value in bacon (that would need an assignment statement: bacon = bacon + 1)

Why does this expression cause an error? How can you fix it? 'I have eaten ' + 99 + ' burritos.'

The expression causes an error because 99 is an integer, and only strings can be concatenated to other strings with the + operator. The correct way is I have eaten ' + str(99) + ' burritos.'.

What three functions can be used to get the integer, floating-point number, or string version of a value?

The int(), float(), and str() functions will evaluate to the integer, floating-point number, and string versions of the value passed to them.