{"id":2289,"date":"2020-01-06T15:10:08","date_gmt":"2020-01-06T15:10:08","guid":{"rendered":"https:\/\/www.askpython.com\/?p=2289"},"modified":"2023-02-16T19:57:20","modified_gmt":"2023-02-16T19:57:20","slug":"python-encode-and-decode-functions","status":"publish","type":"post","link":"https:\/\/www.askpython.com\/python\/string\/python-encode-and-decode-functions","title":{"rendered":"Python encode() and decode() Functions"},"content":{"rendered":"\n

Python’s encode<\/code> and decode<\/code> methods are used to encode and decode the input string, using a given encoding. Let us look at these two functions in detail in this article.<\/p>\n\n\n\n

\n\n\n\n

Encode a given String<\/h2>\n\n\n\n

We use the encode()<\/code> method on the input string, which every string object has.<\/p>\n\n\n\n

Format<\/strong>:<\/p>\n\n\n

\ninput_string.encode(encoding, errors)\n<\/pre><\/div>\n\n\n
This encodes input_string<\/code> using encoding<\/code>, where errors<\/code> decides the behavior to be followed if, by any chance, the encoding fails on the string.<\/p>\n\n\n\n
encode()<\/code> will result in a sequence of bytes<\/code>.<\/p>\n\n\n
\ninp_string = 'Hello'\nbytes_encoded = inp_string.encode()\nprint(type(bytes_encoded))\n<\/pre><\/div>\n\n\n
This results in an object of <class 'bytes'><\/code>, as expected:<\/p>\n\n\n
\n<class 'bytes'>\n<\/pre><\/div>\n\n\n
The type of encoding to be followed is shown by the encoding<\/code> parameter. There are various types of character encoding schemes, out of which the scheme UTF-8<\/strong> is used in Python by default.<\/p>\n\n\n\n
Let us look at the encoding<\/code> parameter using an example.<\/p>\n\n\n
\na = 'This is a simple sentence.'\n\nprint('Original string:', a)\n\n# Decodes to utf-8 by default\na_utf = a.encode()\n\nprint('Encoded string:', a_utf)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nOriginal string: This is a simple sentence.\nEncoded string: b'This is a simple sentence.'\n<\/pre><\/div>\n\n\n
NOTE<\/strong>: As you can observe, we have encoded the input string in the UTF-8 format. Although there is not much of a difference, you can observe that the string is prefixed with a b<\/code>. This means that the string is converted to a stream of bytes, which is how it is stored on any computer. As bytes! <\/p>\n\n\n\n
This is actually not human-readable and is only represented as the original string for readability, prefixed with a b<\/code>, to denote that it is not a string, but a sequence of bytes.<\/p>\n\n\n\n
\n\n\n\n
Handling errors<\/h3>\n\n\n\n
There are various types of errors<\/code>, some of which are mentioned below:<\/p>\n\n\n\n
Type of Error<\/strong><\/td>Behavior<\/strong><\/td><\/tr>
strict<\/code><\/td>Default<\/strong> behavior which raises UnicodeDecodeError<\/code> on failure.<\/td><\/tr>
ignore<\/code><\/td>Ignores<\/strong> the un-encodable Unicode from the result.<\/td><\/tr>
replace<\/code><\/td>Replaces<\/strong> all<\/em> un-encodable Unicode characters with a question mark (?<\/code>)<\/td><\/tr>
backslashreplace<\/code><\/td>Inserts<\/strong> a backslash escape sequence (\\uNNNN<\/code>) instead of un-encodable Unicode characters.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Let us look at the above concepts using a simple example. We will consider an input string where not all characters are encodable (such as \u00f6<\/code>),<\/p>\n\n\n
\na = 'This is a bit m\u00f6re c\u00f6mplex sentence.'\n\nprint('Original string:', a)\n\nprint('Encoding with errors=ignore:', a.encode(encoding='ascii', errors='ignore'))\nprint('Encoding with errors=replace:', a.encode(encoding='ascii', errors='replace'))\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nOriginal string: This is a m\u00f6re c\u00f6mplex sentence.\nEncoding with errors=ignore: b'This is a bit mre cmplex sentence.'\nEncoding with errors=replace: b'This is a bit m?re c?mplex sentence.'\n<\/pre><\/div>\n\n\n
\n\n\n\n
Decoding a Stream of Bytes<\/h2>\n\n\n\n
Similar to encoding a string, we can decode a stream of bytes to a string object, using the decode()<\/code> function.<\/p>\n\n\n\n
Format:<\/p>\n\n\n
\nencoded = input_string.encode()\n# Using decode()\ndecoded = encoded.decode(decoding, errors)\n<\/pre><\/div>\n\n\n
Since encode()<\/code> converts a string to bytes, decode()<\/code> simply does the reverse.<\/p>\n\n\n
\nbyte_seq = b'Hello'\ndecoded_string = byte_seq.decode()\nprint(type(decoded_string))\nprint(decoded_string)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\n<class 'str'>\nHello\n<\/pre><\/div>\n\n\n
This shows that decode()<\/code> converts bytes to a Python string.<\/p>\n\n\n\n
Similar to those of encode()<\/code>, the decoding<\/code> parameter decides the type of encoding from which the byte sequence is decoded. The errors<\/code> parameter denotes the behavior if the decoding fails, which has the same values as that of encode()<\/code>.<\/p>\n\n\n\n
\n\n\n\n
Importance of encoding<\/h2>\n\n\n\n
Since encoding and decoding an input string depends on the format, we must be careful when encoding\/decoding. If we use the wrong format, it will result in the wrong output and can give rise to errors.<\/p>\n\n\n\n
The below snippet shows the importance of encoding and decoding. <\/p>\n\n\n\n
The first decoding is incorrect, as it tries to decode an input string which is encoded in the UTF-8 format. The second one is correct since the encoding and decoding formats are the same.<\/p>\n\n\n
\na = 'This is a bit m\u00f6re c\u00f6mplex sentence.'\n\nprint('Original string:', a)\n\n# Encoding in UTF-8\nencoded_bytes = a.encode('utf-8', 'replace')\n\n# Trying to decode via ASCII, which is incorrect\ndecoded_incorrect = encoded_bytes.decode('ascii', 'replace')\ndecoded_correct = encoded_bytes.decode('utf-8', 'replace')\n\nprint('Incorrectly Decoded string:', decoded_incorrect)\nprint('Correctly Decoded string:', decoded_correct)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nOriginal string: This is a bit m\u00f6re c\u00f6mplex sentence.\nIncorrectly Decoded string: This is a bit m\ufffd\ufffdre c\ufffd\ufffdmplex sentence.\nCorrectly Decoded string: This is a bit m\u00f6re c\u00f6mplex sentence.\n<\/pre><\/div>\n\n\n
\n\n\n\n
Conclusion<\/h2>\n\n\n\n
In this article, we learned how to use the encode()<\/code> and decode()<\/code> methods to encode an input string and decode an encoded byte sequence. <\/p>\n\n\n\n
We also learned about how it handles errors in encoding\/decoding via the errors<\/code> parameter. This can be useful for encryption and decryption purposes, such as locally caching an encrypted password and decoding them for later use.<\/p>\n\n\n\n
References<\/h2>\n\n\n\n
  • JournalDev article on encode-decode<\/li><\/ul>\n\n\n\n
    \n","protected":false},"excerpt":{"rendered":"
    Python’s encode and decode methods are used to encode and decode the input string, using a given encoding. Let us look at these two functions in detail in this article. Encode a given String We use the encode() method on the input string, which every string object has. Format: This encodes input_string using encoding, where […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-2289","post","type-post","status-publish","format-standard","hentry","category-string"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/posts\/2289","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/comments?post=2289"}],"version-history":[{"count":0,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/posts\/2289\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/media?parent=2289"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/categories?post=2289"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/tags?post=2289"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}