In Python, some characters serve different functions and so cannot be displayed or printed like other characters. These characters are referred to as special characters.
For example, double quotes (") and single quotes (') are considered special characters by Python. Their job is to let Python know when a string declaration starts / ends.
That's why in the previous lesson we ran into problems when trying to have a single quote inside a string that is surrounded by single quotes:
print('My name's Andy')
We've found an elegant solution to this and that was by changing the type of quotes we surround our string in:
print("My name's Andy")
print('Double quotes "inside double" quotes')
But what if we wanted to print a string that contains both single and double quotes such as After "Coding 101" we'll solve some problems ?
Let's try to surround this text by single quotes:
print('After "Coding 101" we'll solve some problems')
That doesn't work. It produces a SyntaxError.
Maybe surrounding the text by double quotes will work:
print("After "Coding 101" we'll solve some problems")
Not really. It also produces a SyntaxError.
Character escaping comes to our rescue!
Escaping characters:
There is a way to print special characters like these in Python, and that is by using the backslash character (\).
When we put \ before a special character, we tell Python:
"Hey, I know this is a special character, but I don't want to use it like that here. I just want to print it like I print any other character."
For example, when putting a \ before a quote, Python no longer interprets that as being the end of the string:
print('My name\'s Andy')
print("Double quotes \"inside double\" quotes")
print("After \"Coding 101\" we'll solve some problems")
print('After "Coding 101" we\'ll solve some problems')
The output of this code is:
My name's Andy
Double quotes "inside double" quotes
After "Coding 101" we'll solve some problems
After "Coding 101" we'll solve some problems
Escaping backslash:
Sometimes we might want to print strings that contain character \, such as a file path in your PC:
print('C:\Users\Andy\Games')
This code looks perfectly fine at first sight, but if you run it, it would produce a SyntaxError.
When the interpreter reaches \U, it supposes that you are trying to escape character U, which is not a special character thus cannot be escaped.
Now that you've learned about its function, what type of character do you think \ is in Python? It's a special character!
And like any special character, it can also be escaped by putting another \ in front of it (\\):
print('C:\\Users\\Andy\\Games')
The output of this code is:
C:\Users\Andy\Games
New line character:
Similarly, the escape sequence can be used to make an otherwise printable character serve a special function.
For example, the letter n can be printed normally, but adding a backslash before it (\n) will indicate the start of a new line:
print("Hello world!\nWhat a good day for coding!\n")
print("Let\'s have a blast!")
The output of this code is:
Hello world!
What a good day for coding!
Let's have a blast!
Notice the empty line after What a good day for coding! ?
That's one new line from the \n plus the new line that print() prints no matter what the message is.
Assignment
Follow the Coding Tutorial and let's escape some characters!
Hint
Look at the examples above if you get stuck.
In this lesson, we will explore the concept of escaping characters in Python. This is a fundamental topic that is crucial for handling strings that contain special characters. Understanding how to escape characters allows you to manage strings more effectively, especially when dealing with file paths, quotes within strings, and other special characters.
Special characters in Python include quotes, backslashes, and other characters that have a specific function in the language. For instance, single quotes (') and double quotes (") are used to define string literals. If you need to include these characters within a string, you must use an escape character (\) to indicate that they should be treated as regular characters.
Here are some basic examples:
print('It\'s a sunny day')
print("He said, \"Hello!\"")
The key concept here is the use of the backslash (\) as an escape character. This tells Python to treat the following character as a literal character rather than a special character. This is particularly useful for including quotes within strings and for other special characters like newlines (\n).
For example:
print('She said, "It\'s a beautiful day!"')
print("File path: C:\\Users\\Name\\Documents")
Let's look at some practical examples:
# Including both single and double quotes in a string
print('After "Coding 101" we\'ll solve some problems')
# File paths in Windows
print('C:\\Users\\Andy\\Games')
# Newline character
print("Hello world!\nWhat a good day for coding!\n")
These examples demonstrate how escaping characters can be used in various contexts, such as including quotes within strings, handling file paths, and adding newlines.
One common mistake is forgetting to escape special characters, which can lead to syntax errors. Another pitfall is overusing escape characters, which can make the code harder to read. Here are some best practices:
r'' or r"") for file paths to avoid escaping backslashes.''' or """) for strings that contain both single and double quotes.# Using raw strings for file paths
print(r'C:\Users\Andy\Games')
# Using triple quotes for complex strings
print("""After "Coding 101" we'll solve some problems""")
For more advanced string handling, you can use formatted string literals (f-strings) introduced in Python 3.6. These allow you to include variables and expressions inside strings easily.
name = "Andy"
print(f"My name's {name}")
F-strings automatically handle escaping for you, making your code cleaner and more readable.
Here is a comprehensive example that demonstrates various ways to escape characters in Python:
# Escaping single and double quotes
print('It\'s a sunny day')
print("He said, \"Hello!\"")
# Including both single and double quotes in a string
print('After "Coding 101" we\'ll solve some problems')
# File paths in Windows
print('C:\\Users\\Andy\\Games')
# Newline character
print("Hello world!\nWhat a good day for coding!\n")
# Using raw strings for file paths
print(r'C:\Users\Andy\Games')
# Using triple quotes for complex strings
print("""After "Coding 101" we'll solve some problems""")
# Using f-strings
name = "Andy"
print(f"My name's {name}")
When debugging issues related to escaping characters, carefully check the placement of your backslashes. Ensure that each special character is properly escaped. Writing tests for your string handling functions can help catch errors early.
def test_escape_characters():
assert 'It\'s a sunny day' == "It's a sunny day"
assert "He said, \"Hello!\"" == 'He said, "Hello!"'
assert 'C:\\Users\\Andy\\Games' == r'C:\Users\Andy\Games'
test_escape_characters()
When dealing with complex strings, break down the problem into smaller parts. Handle one type of special character at a time. Use raw strings and triple quotes where appropriate to simplify your code.
Practice by writing small scripts that handle different types of strings, such as file paths, quotes within quotes, and multiline strings.
Mastering the concept of escaping characters in Python is essential for effective string handling. It allows you to include special characters in your strings without causing syntax errors. Practice these techniques to become proficient in managing strings in Python.