Python Beginner Summary

The bottom of the summary is on the Python3.

One. Basis

1. Output and Input:

Output: Print (variable/string)

Enter: input () returns a string

price=input ()print(price)

2.python style

(1) Note #

(2) The general situation is that a line ends the sentence, but if you want to continue, the end of the line is added \

(3) Symbols that do not require line breaks or can be wrapped: ' '

(4) A row can have more than one statement,

3. Identifiers

Basic and Java-like, but also case-sensitive

Key words:

4. Expressions

(1) Determining the type by value

(2) Assigning values in a "reference" manner

(3) Increment operator:+ = = *=/=%= * = <<= >>= &= ^= |=

5.python Data types

(1) (long) Integer: Integral type and long integer type are not strictly differentiated, the integer value after the "L" is the long integer type

(2) Boolean: Only 2 values: True, False, essentially using integer 1, 0, respectively, stored

(3) floating point number: That is, the real number in mathematics, can be similar to scientific notation

(4) plural type: real + imaginary is plural, imaginary part must have J

Complex numbers can separate real and imaginary parts: complex numbers. Real plural. imag

Conjugation of complex numbers: complex numbers. Conjugate ()

(5) String: Single, double, and triple quotes are strings, immutable types

(6) List: powerful type, square brackets [] bounds, mutable type

(7) Tuples: Similar to lists, with parentheses (), immutable types

(8) Mapping type dictionary: curly braces {} bounds, similar to hash table key-value pairs

6 operator

Powers * *, plus sign +-, multiplication */, divisible//, remainder%, plus minus +-

Integer division returns the floating-point number, to get the integer result using//

7. Comparison operations

Comparison of values: by value ratio

Comparison of strings: by ASCII value size

Not equal to "! =" only, "<>" is not supported

8. Logic operation:

Logical operator Precedence: not, and, or

9. Character operators:

Primitive string operator (R/R): – For some places where you do not want the escape character to work
Unicode string operator (u/u): – Converts to a Unicode string

f = open (R'c:\python\test.py','w')    = open ( ' c:\python\test.py ','w')     #会报错

10 built-in functions

The built-in function does not need import to be used, but not the built-in function requires an import

 from Import *print(Floor (-35.4))

Python often uses an "import module" to reuse functions, classes, and the like in off-the-shelf modules into other code blocks

Import Math Print (Math.PI)

Importing multiple modules

Import ModuleName1, ModuleName2, ...

Module to import the specified module attribute, which is the specified name into the current with domain

 from Import Moduleelement

11 packs

A hierarchical file directory structure that defines a Python application execution environment consisting of modules and sub-packages

#方式一
Import  AAA. CCC.C1AAA.CCC.C1.FUNC1 (123)
#方式二
 from Import func1 func1 (123)

12 Library

A library is a set of modules that have related functionality

Two. Aspects of

Python Beginner Summary