Literals

In Python programs we often specify strings directly. This is a string literal: a string that is part of the program itself (in quotes).

For paths, particularly on Windows, we can use "r" to avoid having to escape path separators. And for newlines, we can use triple-quoted literals.

Triple-quoted

This literal syntax form begins and ends with three quotes. Newlines are left as is. In triple-quoted syntax, we do not need to escape quotes.

Note In this syntax, the Python interpreter scans for three quotes for the start and end of the literal. A single quote can also be used.

Note 2 We must surround a triple-quoted string with the same kind of quotes. Double quotes must be matched with double quotes.

# Use a triple-quoted string.
v = """This string has
triple "quotes" on it."""

print(v)This string has
triple "quotes" on it.

Parentheses

We can place parentheses around string literals on separate lines to combine them into one string literal. This syntax is an alternative to triple-quoted in certain cases.

Detail It is best to use standard syntax like triple-quoted strings. Here we combine three string literals into one.

# Surround string literals with parentheses to combine them.
lines = ("cat "
         "bird "
         "frog")

print(lines)
cat bird frog

Raw literals

By prefixing a string literal with an r, we specify a raw string. In a raw string, the backslash character does not specify an escape sequence—it is a regular character.

Tip Raw string literals are ideal for regular expression patterns. In "re" we often use the backslash.

Here The "123" is treated as an escaped sequence in the normal string literal, but not in the raw one.

Detail For file paths or folder paths, raw string literals are ideal. They eliminate confusion about slashes or backslashes on Windows.

# In a raw string "\" characters do not escape.
raw = r"\directory\123"
val = "\directory\123"

print(raw)
print(val)\directory\123
\directoryS

Format literal, f

We can prefix a string with the "f" character to specify a format literal. Variables in the current scope are placed inside the curly brackets surrounding their names.

brick_color = "red"
brick_size = 50

# Use format literal.
result = f"the brick weighs {brick_size} and is {brick_color}"
print(result)
the brick weighs 50 and is red

Add, multiply

A string can be added to another string. And it can be multiplied by a number. This copies that same string into a new string the specified number of times.

Warning If you multiply a string against a large number, you may get a MemoryError. An if-check to prevent this may be helpful.

s = "abc?"

# Add two strings together.
add = s + s
print(add)

# Multiply a string.
product = s * 3
print(product)abc?abc?
abc?abc?abc?

A review

String literals are everywhere in Python programs. For file paths, raw literals (with r) are an ideal syntax. We rarely multiply strings, but this too is possible.