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This article introduces the relevant knowledge of "what is the meaning of% and ~ in python". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

What are the meanings of%?

Find the manual

Refer to the appendix index section of the "The Python Libary Reference" python library guide (P1899):

% (percent):

Datetime format, 198, 594, 596

Environment variables expansion (Windows), 377,1798

Interpolation in configuration files, 493

Operator, 31

Printf-style formatting, 51, 65

Itemized according to the usage index in index:

Datetime format: represents the date format

Environment variables expansion environment variable extension

Interpolation in configureation files insert Settings File

Operator: take surplus

Printf-style formatting: output formatting

Environment variable extension:

Expands environment variable placeholders% NAME% in strings like REG_EXPAND_SZ:

ExpandEnvironmentStrings ('% windir%')

'C:\\ Windows'

Insert settings file

Home_dir: / Users

My_dir:% (home_dir) s/lumberjack

My_pictures:% (my_dir) s/Pictures

Example:

Cls_info = ['% s\ n (% d% s)'% (estimator_conf ['name'], estimator_conf [' complexity_computer'] (estimator_conf ['instance']), estimator_conf [' complexity_label']) for estimator_conf in configuration ['estimators']] ~ what does it mean?

Check the manual:

(tilde)

Home directory expansion, 377

Operator, 32

In addition to representing the home directory, the representation operator is the bits of inverted

~ 5cm Murray 6

~-11: 10

It can be understood as taking 0 as the first positive number and the axis symmetry point of the coordinate.

For analysis, see ↓.

Bitwise inverse operator

Bitwise inverse operator ~ rarely used, today see "byte of Python" book examples, here to learn, and then review the basic knowledge of the computer.

The bitwise inverse operator is used to reverse a binary number bitwise, that is, 0 to 1, 1 to 0, and supposedly decimal 5 (0000 0101) should be (1111 1010) decimal 250. however, this is not the case in Python, and the result is as follows:

~-6

five

There are three ways to express the number of symbols in a computer, namely, the original code, the inverse code and the complement code. The three representation methods all have two parts: symbolic bit and numerical bit. The symbolic bit is 0 for "positive" and 1 for "negative", while the numerical bit is different. In computer systems, numerical values are always represented and stored by complements. The reason is that symbol bits and numerical ranges can be processed uniformly by using complements, and addition and subtraction can also be handled uniformly.

The complement of a positive integer is its binary representation, the same as the original code.

The complement of a negative integer whose corresponding positive binary denotes all bits (including symbolic bits, 0 to 1, 1 to 0) and then adds 1.

Python bitwise inverse operation:

~-6

five

Operational analysis:

The complement of-6 is + 6 (0000 0110) and then + 1, which is (1111 1001) + (0000 0001) = (1111 1010), that is,-6 in the computer is stored in (1111 1010), and (1111 0101) is obtained by bit-by-bit inversion. This is the answer 5.

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