A value is one of the basic things a program works with, like a letter or a number. Some values we have seen so far are
These values belong to different types:
2 is an integer,
42.0 is a floating-point number, and
'Hello, World!' is a string, so-called because the letters it contains are strung together.
If you are not sure what type a value has, the interpreter can tell you:
>>> type(2) <class 'int'> >>> type(42.0) <class 'float'> >>> type('Hello, World!') <class 'str'>
In these results, the word “class” is used in the sense of a category; a type is a category of values.
Not surprisingly, integers belong to the type
int, strings belong to
str and floating-point numbers belong to
What about values like
'42.0'? They look like numbers, but they are in quotation marks like strings.
>>> type('2') <class 'str'> >>> type('42.0') <class 'str'>
When you type a large integer, you might be tempted to use commas between groups of digits, as in
1,000,000. This is not a legal integer in Python, but it is legal:
>>> 1,000,000 (1, 0, 0)
That’s not what we expected at all! Python interprets
1,000,000 as a comma-separated sequence of integers. We’ll learn more about this kind of sequence later.