strings.pdf

Introduction to Computer Programming Strings

Strings are one of Python’s primary data types.
Strings can be used to represent anything that can be
encoded as text.
Examples: symbols, words, text
fi
les, Python programs, and
web pages.
We’ve already been using strings quite a bit and will now
focus on accessing and processing them.
String Data Type

All characters have a corresponding character code.
Python uses Unicode to assign character codes.
Unicode is a common standard for encoding thousands of
symbols and characters from many languages.
The ord() function can be used to get the Unicode number
for any character.
The chr() function can be used to get the character for any
Unicode number.
Characters

“Escape characters” are a special notation for whitespace and
other unprintable characters.
Used for characters without a standard symbol or symbols
Python sets aside.
Escape characters begin with a backslash:
Escape sequences are considered one character.
Escape Characters

ASCII Table

Strings are de
fi
ned as ordered collections of characters.
Therefore, we can access these characters by position with
“indexing.”
Offsets start at 0 and end at one less than the length of the
string.
Offset can also be speci
fi
ed negatively.
String Indexing

0 1 2 3 4 5
p y t h o n
-6 -5 -4 -3 -2 -1

Slicing is for extracting substrings from a string.
To slice a string, indicate the
fi
rst character you want and one
past the last character.
First index location is always 0.
Last index location is always the length of the string minus
one.
String Slicing

Testing methods
Searching methods
Formatting methods
Stripping methods
Splitting methods
Replacement methods
String Methods

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