Python: Quote String

What is String

A string is a sequence of characters.

• In Python 3, it's a sequence of Unicode characters.
• In Python 2, it's a sequence of bytes (representing ASCII Characters). But if prefixed with u, then it's a sequence of Unicode characters.

Python string is immutable. Any function that work on string returns a new string.

Quoting String

Two ways to quote a string.

• Singe quote. e.g. "abc" → does not allow literal newline.
• Triple quote. e.g. """abc""" → for multi-line string. (allow literal newline)

String Delimiter

String can be quoted by QUOTATION MARK e.g. "abc" or APOSTROPHE e.g. 'abc' .

There is no different between them.

No Here-String

Python does not suport here-doc or here-string, as in Perl, PHP, PowerShell.

Single Quote String

String can be created by:

• "QUOTATION MARK delimited"
• 'APOSTROPHE delimited'

they are effectively the same.

Literal linebreak is not allowed. It's syntax error.

xx = "this is string"

yy = 'another string'

print(xx, yy)

# Literal linebreak is not allowed

xx = "abc
xyz"

#     xx = "abc
#             ^
# SyntaxError: EOL while scanning string literal
# error: cannot format -: Cannot parse: 1:3: a = "abc

Triple Quote String

• Python: Triple Quote String

String Prefix Char

a character may be prefixed to a string, to make the string of a particular type.

prefix chars:

• u"abc" → means unicode string, in python 2. In python 3, all string are Python: Unicode 🐍, the u prefex has no meaning.
• f"abc" → means f-String, where {…} means embedded expression.
• r"abc" → means Raw String. Escape Sequence is ignored.
• b"abc" → means byte sequence.

these prefix characters may be combined. e.g. fr"abc" means can embed expression and also raw (ignore Python: String Escape Sequence)

String Escape

Inside string (except Raw String ):

• Use \n for linebreak.
• Use \" for double quote.
• Use \' for single quote.

• Python: String Escape Sequence