{"id":4305,"date":"2020-03-26T13:52:37","date_gmt":"2020-03-26T13:52:37","guid":{"rendered":"https:\/\/www.askpython.com\/?p=4305"},"modified":"2022-08-06T13:12:34","modified_gmt":"2022-08-06T13:12:34","slug":"python-string-casefold","status":"publish","type":"post","link":"https:\/\/www.askpython.com\/python\/string\/python-string-casefold","title":{"rendered":"Python String casefold()"},"content":{"rendered":"\n

The Python String<\/a> casefold() method returns a case folded string, and we use this to remove all case distinctions in a string.<\/p>\n\n\n\n

Let’s look at what this means.<\/p>\n\n\n\n

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Using the Python String casefold() method<\/h2>\n\n\n\n

This belongs to the String<\/code> class, and can be used only on String objects.<\/p>\n\n\n\n

The Syntax for this method is:<\/p>\n\n\n

\nstring_obj.casefold()\n<\/pre><\/div>\n\n\n
This will return a new string, after applying all case folds.<\/p>\n\n\n\n
For example, it will convert all uppercase letters to lowercase.<\/p>\n\n\n
\nmy_str = "Hello from AskPython"\n\ncasefolded_str = my_str.casefold()\n\nprint(casefolded_str)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nhello from askpython\n<\/pre><\/div>\n\n\n
This converts all uppercase letters to lowercase ones for the English alphabet.<\/p>\n\n\n\n
But what if the string has characters from another language, and in another encoding? The Python string casefold() method solves this problem.<\/p>\n\n\n\n
Take an example of the German lowercase letter ‘\u00df<\/code> ‘. This corresponds to the English string “ss”, since there is an encoding for German alphabets, and we decode it to an English string.<\/p>\n\n\n\n
If we were to use the lower()<\/code> method on this alphabet, it would do nothing, since the letter is already in lowercase, so the output will remain ‘ \u00df<\/code> ‘.  Python string casefold() not only converts to lowercase, but also makes sure we get back our English string “ss”.<\/p>\n\n\n\n
The below screenshot shows this difference.<\/p>\n\n\n\n
\"German
German String Casefold<\/figcaption><\/figure><\/div>\n\n\n\n
Let’s take one more example, to show that the strings ‘\u00df<\/code>‘ and “SS” will resolve to the same casefolded string “ss”.<\/p>\n\n\n
\ns1 = '\u00df'\ns2 = 'ss'\ns3 = 'SS'\nif s1.casefold() == s2.casefold():\n    print('Casefolded strings of s1 and s2 are equal')\nelse:\n    print('Casefolded strings of s1 and s2 are not equal')\n\nif s1.casefold() == s3.casefold():\n    print('Casefolded strings of s1 and s3 are equal')\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nCasefolded strings of s1 and s2 are equal\nCasefolded strings of s1 and s3 are equal\n<\/pre><\/div>\n\n\n
Indeed, both these strings resolve to the same casefolded string!<\/p>\n\n\n\n
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Conclusion<\/h2>\n\n\n\n
In this article, we learned how we could use the Python string casefold()  method in Python.<\/p>\n\n\n\n
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References<\/h2>\n\n\n\n