Data TypesΒΆ

If you are not sure what class (data type) a value falls into, Python has a function called type which can tell you.

What about values like "17" and "3.2"? They look like numbers, but they are in quotation marks like strings.

They’re strings!

Strings in Python can be enclosed in either single quotes (') or double quotes ("), or three of each (''' or """)

Double quoted strings can contain single quotes inside them, as in "Bruce's beard", and single quoted strings can have double quotes inside them, as in 'The knights who say "Ni!"'. Strings enclosed with three occurrences of either quote symbol are called triple quoted strings. They can contain either single or double quotes:

Triple quoted strings can even span multiple lines:

Python doesn’t care whether you use single or double quotes or the three-of-a-kind quotes to surround your strings. Once it has parsed the text of your program or command, the way it stores the value is identical in all cases, and the surrounding quotes are not part of the value.

So the Python language designers usually chose to surround their strings by single quotes. What do think would happen if the string already contained single quotes?

When you type a large integer, you might be tempted to use commas between groups of three digits, as in 42,000. This is not a legal integer in Python, but it does mean something else, which is legal:

Well, that’s not what we expected at all! Because of the comma, Python chose to treat this as a pair of values. In fact, a print statement can print any number of values as long as you separate them by commas. Notice that the values are separated by spaces when they are displayed.

Remember not to put commas or spaces in your integers, no matter how big they are. Also revisit what we said in the previous chapter: formal languages are strict, the notation is concise, and even the smallest change might mean something quite different from what you intended.

Note

The examples in this online text describe how print works in Python 2.7. If you install Python 3 on your machine, it will work slightly differently. One difference is that print is called as a function, with parentheses around the values to be printed.

Check your understanding

Next Section - Type conversion functions