String Manipulation

12.1 List of Methods

In Python, the string data type comes with a rich set of methods that make working with strings convenient and powerful. Here are some of the most popular methods of the string class:

Note that a str object cannot be changed after it's created. All functions that modify the string actually return a new object. The old object remains unchanged.

12.2 Most Popular Methods

Let's go through some of the simpler and more popular methods.

Method strip():

Removes whitespace from the beginning and end of the string.

text = "  hello world!  "
cleaned_text = text.strip()
print(cleaned_text)  # Output: "hello world!"
        

Method lower():

Converts all characters in the string to lowercase.

text = "Hello World!"
lower_text = text.lower()
print(lower_text)  # Output: "hello world!"
            
        

Method upper():

Converts all characters in the string to uppercase.

text = "Hello World!"
upper_text = text.upper()
print(upper_text)  # Output: "HELLO WORLD!"
        

Method split(separator):

Splits the string into a list of substrings based on the given separator.

text = "one,two,three"
parts = text.split(',')
print(parts)  # Output: ['one', 'two', 'three']
        

Method join(iterable):

Joins a collection of strings into one string using a separator string.

parts = ['one', 'two', 'three']
joined_text = ','.join(parts)
print(joined_text)  # Output: "one,two,three"
        

Important! Note that the join() method is called on the separator string!

These methods are key tools for processing and manipulating text data in Python.

12.3 Searching and Replacing Substrings

There are a few other popular methods for searching and replacing strings within a string.

Method find(substring):

Returns the index of the first occurrence of the substring in the string or -1 if the substring is not found.

text = "hello world"
index = text.find("world")
print(index)  # Output: 6
        

Method index(substring):

Similar to find, but raises a ValueError exception if the substring is not found.

text = "hello world"
try:
    index = text.index("world")
    print(index)  # Output: 6
except ValueError:
    print("Substring not found")
        

Method replace(old, new):

Replaces all occurrences of the substring old with the substring new.

text = "hello world"
replaced_text = text.replace("world", "everyone")
print(replaced_text)  # Output: "hello everyone"
        

Method startswith(prefix):

Checks if the string starts with the specified prefix.

text = "hello world"
print(text.startswith("hello"))  # Output: True 
        

Method endswith(suffix):

Checks if the string ends with the specified suffix.

text = "hello world"
print(text.endswith("world"))  # Output: True
        

These methods are very handy for various string searching, replacing, and checking operations, simplifying text data handling.

2

Task

Python SELF EN, level 10, lesson 4

Locked

Cleaning

Cleaning

Open

2

Task

Python SELF EN, level 10, lesson 4

Locked

Reordering.

Reordering.

Open