What kind of language python
编译型
执行速度快
开发速度慢
解释型
执行速度慢
开发速度快variable
a = 35 +36
print（a）
b = a * 2
print(b)
pring(1+a)
a = "香水" # 声明变量Variable frequently used in the program
Variable rules
1. 变量 由字母，数字，下划线组成
2. 数字不能开头
3. 不能使用python关键字
4. 不能使用中文和拼音
5. 区分大小写
6. 变量名要具有描述性意义
7. 推荐写法
驼峰体
大峰
小峰
下划线
age_of_oldboy = 98(官方推荐)
constant
Constant is declared in the configuration file
ID = 11111111111
age = 18
age1 = 19
age2 = age
age = 20
print(age,age1 age2)
Operational priorities: equal sign on the right> left
Note
Single-line comments (comment when the row) "", '', as line
Multi-line comments
"" "" "", '' '' '' May wrap, but must first multi-wall quotes
Underlying type
Int int 1 .... ∞ for calculating and comparing the
The string "Hello" in python as long as the quotes of this is due to a string
a = "1"
b = "2"
c = "3"
print (a + b + c) # string concatenation
d = "Television"
print (d * 8) # string can only multiply the number
'' 'My name's "meet"' '' with the use of quotation marks
Boolean value
Returns the truth value for determining
True
False
print(3>2) T
print(3<2) F
User interaction
input () # user interaction
intput ( "precautionary statements")
input acquired are strings
a = input("请输入账号，然后回车：") # input获取到的都是字符串
print(int(a)+5)
Control flow statements
Single if
Keyword space colon condition
Indent results
if 3 > 2:
a = input("asd")
print(a)
print(1)
if 3<2:
print(2)
print(3)
if else a second election
if the space colon condition
Indent results
else colon
Indent results
a = int (input ( "Enter"))
if a > 10:
print(1)
else:
print(2)
if elif elif a multiple choice or zero
print(110)
if 3<2:
print("A")
elif 3>8:
print("B")
elif 5 <0:
print("C")
print(112)
if elif else a multiple-choice
if 3 == 2:
print(1)
elif 3 < 2:
print(3)
elif 3 > 10:
print(10)
else:
print(9)
if if if multiple choice
if 3>2:
print("A")
print("B")
if 5>2:
pring("C")
if nested
sex = "女"
age = 35
if sex == "女"：
if age == 35：
print ( "come sit.")
else:
print ( "You go next door to find Chunsheng")
else:
print ( "You go door to find alex")
= A 'Alex'
B = 'Alex is a big biscuits'
C = INPUT ( "Please enter the account number")
D = INPUT ( "Please enter the password")
IF A == C:
IF D == B:
Print ( "successful login ")
the else:
Print (" password error ")
the else:
Print (" error account ")
to sum up
A .python history
The difference python2 and python3
The birth of Django framework 2004
Two .python programming language
python is an interpreted language
Three types of .python
Cpython jpython ironpython pypy
IV. Variables
Variables are letters, numbers, underscores
Prohibition start with numbers
Prohibit the use of python keywords
You can not use Chinese and Pinyin
Variable names are case-sensitive generations
Recommended wording
Hump body, underscore
age_of_oldboy = 98 (the official recommended)
A variable name only one in memory
V. Constant
Variable name in all caps is constant - constant modification is not recommended
VI. Notes
Single-line comments
Multi-line comments
VII. Basic data types
int-- integer (numbers) are calculated and compared
str-- string (letters, characters)
Boolean for determining bool--
VIII. User interaction
input () Note: input to obtain the contents of all strings
IX. Flow control statements
Single if
if else a second election
if elif elif a multiple choice or zero
if elif elif else is selected from a plurality of
if if if multiple-choice or more than zero
Analyzing be nested if multilayer layer 3 is generally about nested if
10. Other knowledge
And front and rear and is the true and are true
type () to view the data type
int ( "5") is converted into integer string 5
str (5) to convert an integer to a string
Are equal before and after the determination ==