Python provides an wide range of built-in methods that make string manipulation simple and efficient. In this article, we'll explore several techniques for modifying strings in Python.
Start with doing a simple string modification by changing the its case:
Changing Case
One of the simplest ways to modify a string is by changing its case using string.upper() method which converts all characters in the string to uppercase.
Python
s = "hello world"
print(s.upper())
Other methods of changing case in a python strings are:
- lower(): Converts all characters in the string to lowercase.
- capitalize(): Capitalizes the first character of the string and makes the rest lowercase.
- title(): Capitalizes the first letter of each word in the string.
- swapcase(): Swap the cases of all characters in a string
- capitalize(): Convert the first character of a string to uppercase
Let's take a look at other cases of string modification:
Replacing Substrings
We can replace parts of a string using replace() method. This method takes two arguments: 1) old substring we want to replace and 2) new substring we want to replace it with.
Example:
Python
s1 = "I love Python"
s2 = s1.replace("Python", "programming")
print(s2)
The replace() method returns a new string, so the original string is not modified in place (since strings are immutable in Python).
Trimming Whitespace
Sometimes, strings may have unwanted spaces at the beginning or end. To remove these, we can use the strip() method. This method removes any leading and trailing whitespace from the string.
Python
s = " Hello World! "
print(s.strip())
We can also use lstrip() to remove leading spaces and rstrip() to remove trailing spaces.
Concatenating Strings
Concatenating strings means joining two or more strings together. In Python, we can do this using the + operator.
Python
s1 = "Hello"
s2 = "World"
print(s1 + " " + s2)
OutputHello World
Python is awesome
We can also use join() when concatenating a list of strings.
Slicing Strings
String slicing allows you to extract a portion of a string. We can specify a starting and ending index and Python will return a substring. We can also use the step parameter to skip characters.
Python
s = "Hello, Python!"
print(s[0:5]) # Output: "Hello" (characters from index 0 to 4)
print(s[7:]) # Output: "Python!" (characters from index 7 to the end)
print(s[:5]) # Output: "Hello" (characters from the start to index 4)
print(s[::2]) # Output: "Hoo yhn" (every second character)
OutputHello
Python!
Hello
Hlo yhn
Checking for Substrings
To check if a string contains a certain substring, we can use in keyword .
Python
s = "Python is fun"
print("Python" in s)
The in keyword returns True if the substring is found . We can also use find() method which returns the index of the first occurrence of the substring (or -1 if it's not found).
Python allows we to format strings in a readable way using f-strings (formatted string literals), which were introduced in Python 3.6. We can insert variables or expressions inside a string using curly braces {}.
Python
s = "Geek"
print(f"name - {s}")
For earlier versions of Python, we can use the format() method.
You can learn more about string methods with our String Methods Article.
