casefold() string in Python

The casefold() method in Python converts a string to lowercase, making it ideal for case-insensitive string comparisons. Unlike lower(), casefold() handles special Unicode characters more aggressively, making it the preferred choice for string matching.

Syntax

string.casefold()

This method takes no parameters and returns a new string with all characters converted to lowercase.

Basic Usage

Here's how to convert a string to lowercase using casefold() ?

string = "BestTutorials"
# print lowercase string
print("Lowercase string:", string.casefold())

Lowercase string: besttutorials

Case-Insensitive String Comparison

You can compare two strings with different cases by applying casefold() to both ?

string1 = "Hello Tutorials"
string2 = "hello tutorials"

string3 = string1.casefold()
string4 = string2.casefold()

if string3 == string4:
    print("Strings are equal after casefold()")
else:
    print("Strings are not equal")

Strings are equal after casefold()

casefold() vs lower()

While both methods convert to lowercase, casefold() is more aggressive with special characters ?

# German eszett character
text = "Straße"

print("lower():", text.lower())
print("casefold():", text.casefold())
print("Are they equal?", text.lower() == text.casefold())

lower(): straße
casefold(): strasse
Are they equal? False

Comparison

Conclusion

Use casefold() for case-insensitive string comparisons, especially with international text. It provides more reliable results than lower() when dealing with special Unicode characters.