• Print () is a function, not a statement

  • Raw_input () input function, input()

  • Python 3 makes a clearer distinction between textual and binary data.

**1.** text is represented by Unicode and is of type STR **2.** Binary data is represented by bytes (byte packets) and is of type bytes

  • New data type Bytes, representing binary data and encoded text strings with a prefix b

  • Python3 converts bytes to STR

**1.** STR can be encoded into bytes **2.**bytes can be decode into STR

  • String formatting output mode: Added format()

  • Dict type changes

Iterkeys (), itervalues(), iteritems(), keys(), values(), items()

String encoding format:

  • **ASCII: ** The encoding method used by early computers to save English characters

  • **GB2312: ** Chinese extension to ASCII

  • **GBK/GB18030: ** includes all the content of GB2312, while adding nearly 20,000 new Chinese characters and symbols

  • **Unicode: ** includes global conformance and encoding. Each character is represented by 3 to 4 bytes, which wastes space

  • **UTF-8: ** Variable-length encoding, the most widely used Unicode implementation on the Internet, determines the character length according to the language, such as 3 bytes for a Chinese character and 1 byte for a letter. It is also the default encoding format in Linux.