# print function

Print (variable name)

Print (variable)

print("hello world") # hello world myString = "hi"; print(myString); # hi

# Single-Line Comments

Single line notes begin with #

# Here are the notes print("hi"); # Here are the notes

# Continuation character

A continuation character is required because a line is too long

If you can judge the logical relationship, you do not need a newline character (two cases)

- The inside of parentheses, brackets and curly braces can be written more
- String under three quotation marks

color1 = "red"; color2 = "blue"; if color1=="blue" and\ color2 == "red": print("yes"); else: print("no");

# One line multiple statements

Write multiple statements in one line

x = 1; y = 2; print(x+y);

It's not usually written like this

Not easy to read

# block

The same indentation is a block, no {} block

# identifier

- Initials are underlined or letters
- The rest can be letters, underscores, numbers
- Case sensitive, i.e. PI and PI are different identifiers

established by the people through long social practice:

- All uppercase is considered a constant
- Try not to start with an underscore. It is considered a private variable
- Hump nomenclature
- See the name and know the meaning

# keyword

Like if, or, else, etc., cannot be used as identifiers

Avoid conflicts with the language itself

# expression

Operator to connect variables and constants

Attention priority

- Arithmetic operators, such as +, -, *, etc
- Bitwise operators, such as negation ~, and &, etc
- Comparison operators, such as >, <, = = and so on
- Logical operators, such as not, and, or

Note that the = sign is an assignment symbol

# Assignment statement

Assignment by reference

Equivalent to a variable

No declaration type is required

Each variable has an id function that returns the unique identifier of the object

>>> a = 500 >>> b = a >>> c = 500 >>> id(a) 2804352670064 >>> id(b) 2804352670064 >>> id(c) 2804352669904 // Here b and c refer to the same 500 // c refers to another 500

>>> a = 1000 >>> b = 1000 >>> id(a) 2804352670224 >>> id(b) 2804352670256 // It can be seen that b in example 1 is actually a reference to a

>>> a = 10 >>> b = 10 >>> id(a) 2804351631888 >>> id(b) 2804351631888 >>> a = 256 >>> b = 256 >>> id(a) 2804351639760 >>> id(b) 2804351639760 >>> a = 257 >>> b = 257 >>> id(a) 2804352670224 >>> id(b) 2804352670320 // In principle, the IDs of a and b should be different in the above three times // But the first two are different, and the third is the same // Why is the same? // Because some numbers are commonly used // python is saved // In the future, these numbers are directly referenced and saved, // This increases speed // Therefore, at 10 and 256, the IDs of a and b are the same, // But it is different at 257, because python only saves - 5 ~ 256

# assignment

Similar to c

Tuple assignment

x = 1 y = 2 x,y = y,x print((x,y)) // (2,1)

Here (x,y) is a tuple

The assignment process here is similar to the deconstruction assignment of js

x,y = y,x

It is equivalent to packing y and X into a tuple (2,1) and assigning it to a temporary variable temp,

Then, after the structure is 2 and 1, it is assigned to X and Y respectively

# sentence

A line of logic code that completely performs a task

For example, an assignment statement

# integer

Similar to C

However, long integers and integers are combined

The specific digits are related to the operating system

One digit represents positive and negative, and the remaining digits represent size

=/-(2^(n-1)), n is the number of bits of the operating system, such as 64 bit operating system

# Boolean

There are only two values: True, False

The essence is that True is stored with 1 and False with 0, so it is a subclass of integer

# float

It's called float in python

It can be expressed by similar scientific counting method

# Plural form

i^2 = -1

Then i is an imaginary number

A real number plus an imaginary number is a complex number

For example, a + bi, where a and B are real numbers, and a and B can be 9

In python, real is used to obtain a, and imag returns b

Use combine() to obtain its conjugate complex number

From the above three sentences, it can be concluded that real and imag should be attributes

And combine is the function name

// Note that in python, j is used to represent the imaginary number unit, and the above i only explains what is an imaginary number >>> a = 1+10j >>> a.imag 10.0 >>> a.real 1.0 >>> a.conjugate() (1-10j) >>>

complex in python

# String representation

Single quote ''

Double quotation mark ""

Three quotation marks (three single quotation marks) ''

Similar to js ` ` ` ` ` ` ` (three backquotes)

# Mapping type (Dictionary)

The only mapping type in python is dictionary

Similar to JSON (key value pair)

d = {key_string : value_any,...}

d[key_string];

Note the key above_ String must be a string

value_any is of any type

# arithmetic operation

special

Power:**

Division://

Multiple divisions

The remainder is the remainder after division

The result of division is the result of / / operation

109 divided by 10 equals 10 remainder 9

That is 109 / / 10 = 10

109%10 = 9

Note - 32 = - (32) = - 9

(-3)**2=0

Pay attention to the operation priority

# Comparison operation

Values are compared by value size

Strings are compared by ASCII value size

be careful

3<4<5

This form

Equivalent to: 3 < 4 and 4 < 5

# Character operator

Raw string operator (r/R)

Can be used where you don't want escape characters to work

r'something'

Because there may be such as \ n in the string

And \ n is understood as line feed. If the path "\ note\math_note" exists,

It may not be resolved correctly,

In this case, you can use r"\note\math_note", so that the escape character will not work

Or use two \ (two \ will be escaped as \)

# function

## Built in function

Can be used directly

## Standard library functions

The python standard specifies the functions to be supported

Import the module to use

## Third party Library

Install a third-party library and then import it for use

## User defined function

User defined functions

//Unfinished to be changed