Getting Started with Python

Basic knowledge

First, Python is an interpreted language, that is, the program does not need to compile, at run time to translate into machine language, every execution once to translate once, so less efficient

Ii. explanatory language and compiled language
Compiled languages

is to first write the program into a computer language and then execute, is called a compile everywhere, such as C, C + + is a compiled language, the language is characterized by the speed of running, but need to pre-compile the program can be.
Interpreted language

is the program at the time of operation, through an interpreter, the code is translated into a computer language and then run, that is, you write the code to run directly, such as Python, Shell, Ruby, Java, Perl, etc. are

Interpreted language, of course, such a language because the principle is not the same, the execution speed is not compiled language fast.

Python applications:

Background service development, data mining, data analysis, artificial intelligence, automated operations, automated testing

　　Single-line Comment: # (shortcut key ctrl+/)

　　Multiline Comment: Double three quotes "" "Single Triple Quote '"

Variable: = Used to assign a value

1 ) variable name rule: ( see name and meaning )

1. Any combination of letters, numbers, underscores 2. The first number must not be the number 3. Variable name it's better to be famous. 4. You cannot use keywords (such as) as variable names

　　

2 ) variable assignment

A variable assignment in Python does not need to specify a data type and can be defined directly.

The equals sign (=) is used to assign a value to a variable. The left side of the equals operator is a variable name, and the right side of the equals operator is the value stored in the variable.

Each variable must be assigned before it is used, and the variable will not be created until the variable is assigned.

The equal sign is followed by either single or double quotation marks, which is a character string character type, an integer after the equal sign, or an int integer, or a float after the equal sign

　　

PS: all English symbols ctrl+d quick copy Line

Variable type (int, float, str)

　　　

Conditional judgment (if condition is judged to be added: Colon )

　　

Single condition judgment Multi-Conditional judgment

Here is a condition two ways of writing (judging gender)

　　　　

　　　　

Little Practice

Cycle

While loop

　　　　

While loop writing guessing games

　　　　

While corresponding to an else, the loop executes after the normal end.

　　　　

For loop

　　　　

Print three times Hello World

　　　　

　　　　

String formatting

　　　　

Little Practice Login Program

Username

passwd

Let the user enter the account number and password

If user name and password input correct prompt you xxx, welcome to login, today's date is XXX, program end

Error, Prompt account/password error

The maximum input three times, if the input 3 times is wrong, the error is too many failures.

Need to determine the input is empty

　　

　　

Getting Started with Python