Character encoding and floating point calculation precision loss problem

1. Character encoding
Characters are encoded in the computer memory using the unicode character set, that is, characters occupy two bytes.
unicode includes Chinese, Korean and other characters. The reason why it replaces the ascll code set is that its character set only includes uppercase and lowercase English characters, numbers and other characters, excluding Chinese, Korean and other characters. unicode is an internationally unified character set.
Characters are stored and transmitted in UTF-8 encoding in many cases in file and network transmission, which can save space and transmission efficiency.
Unicode and utf-8 are automatically converted in file input and output and network transmission.
The default encoding of the window operating system is gbk encoding. For example, to run java files, you need to use the javac -encoding utf-8 command to compile, otherwise there will be garbled characters when running. The java files are encoded in utf-8, so the compilation command needs to use utf-8 for parsing, otherwise there will be an error
Note: The file stored in what encoding has to be parsed with that encoding. The above is a good example.
2. Loss of precision
In java and python, the conversion of floating-point decimal to binary may cause the situation that binary cannot be accurately represented, and the operation result will be inaccurate., such as println(0.1+0.2), the result is 0.3000000004.
In other words, if binary cannot be accurately represented, may have inaccurate operation results.