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Defining the Python String Object
EvoClass-AI001 Lecture 6
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Defining the Python String Object

In Python, the String is the fundamental data type used for representing text. A string is an ordered sequence of Unicode characters. Unlike simple variables, a string is treated as an object, granting it access to powerful, built-in functionality (methods) for manipulation. They are essential for handling nearly all raw input data, such as logs, file content, or web scrape results.

1. Defining and Quoting Strings

Strings are defined by enclosing text in either single quotes (') or double quotes ("). The choice is mainly stylistic, but using double quotes is highly recommended if the text content itself contains apostrophes, as this avoids syntax errors.

str1 = 'Hello World'
str2 = "Python is fun"
# To include an apostrophe, use double quotes:
error_safe = "It's time to learn"
Unicode and Text Data
Python 3 strings natively support Unicode, meaning they can correctly represent characters from almost all global writing systems, making text processing reliable across languages.

2. The String Object Perspective

  • Sequence: Strings are ordered sequences, meaning every character has a specific index or position, starting from zero.
  • Methods: As objects, strings possess dozens of methods (like .upper(), .lower(), and .replace()) allowing for powerful text transformation without external libraries.
  • Immutability: Once a string object is created, its characters cannot be changed in place. Any operation that seems to change a string actually creates a brand new string object in memory.
main.py
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# CODE: Basic String Definition and Properties
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greeting = "Hello Python Learner!"
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course = 'EvoClass AI'
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# Using f-string for dynamic output
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print(f"Course: {course}")
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# Determine the length
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L = len(greeting)
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print(f"Length of greeting: {L}")
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# bad_quote = 'It's time to crash'
TERMINAL bash — 80x24
> Ready. Click "Run" to execute.
>