Strings
If you want to use text in Python, you have to use a string.
A string is created by entering text between two single or double quotation marks.
When the Python console displays a string, it generally uses single quotes. The delimiter used for a string doesn't affect how it behaves in any way.
>>> "Python is fun!"
'Python is fun!'
>>> 'Always look on the bright side of life'
'Always look on the bright side of life'
Some characters can't be directly included in a string. For instance, double quotes can't be directly included in a double quote string; this would cause it to end prematurely.
Characters like these must be escaped by placing a backslash before them.
Other common characters that must be escaped are newlines and backslashes.
Double quotes only need to be escaped in double quote strings, and the same is true for single quote strings.
>>> 'Brian\'s mother: He\'s not the Messiah. He\'s a very naughty boy!'
'Brian's mother: He's not the Messiah. He's a very naughty boy!'
Newlines
Python provides an easy way to avoid manually writing "\n" to escape newlines in a string. Create a string with three sets of quotes, and newlines that are created by pressing Enter are automatically escaped for you.
>>> """Customer: Good morning.
Owner: Good morning, Sir. Welcome to the National Cheese Emporium."""
'Customer: Good morning.\nOwner: Good morning, Sir. Welcome to the National Cheese Emporium.'
Input and Output
Usually, programs take input and process it to produce output.
In Python, you can use the print function to produce output. This displays a textual representation of something to the screen.
>>> print(1 + 1)
2
>>> print("Hello\nWorld!")
Hello
World!
To get input from the user in Python, you can use the intuitively named input function.
The function prompts the user for input, and returns what they enter as a string (with the contents automatically escaped)
>>> input("Enter something please: ")
Enter something please: This is what\nthe user enters!
'This is what\\nthe user enters!'
String Concatenation
As with integers and floats, strings in Python can be added, using a process called concatenation, which can be done on any two strings.
When concatenating strings, it doesn't matter whether they've been created with single or double quotes.
>>> "Spam" + 'eggs'
'Spameggs'
>>> print("First string" + ", " + "second string")
First string, second string
Even if your strings contain numbers, they are still added as strings rather than integers. Adding a string to a number produces an error, as even though they might look similar, they are two different entities.
>>> "2" + "2"
'22'
>>> 1 + '2' + 3 + '4'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'str'
Strings can also be multiplied by integers. This produces a repeated version of the original string. The order of the string and the integer doesn't matter, but the string usually comes first.
Strings can't be multiplied by other strings. Strings also can't be multiplied by floats, even if the floats are whole numbers.
>>> print("spam" * 3)
spamspamspam
>>> 4 * '2'
'2222'
>>> '17' * '87'
TypeError: can't multiply sequence by non-int of type 'str'
>>> 'pythonisfun' * 7.0
TypeError: can't multiply sequence by non-int of type 'float'
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