Control statement ： The order , choice , loop
Selection structure （ Conditional judgment structure ）：
By judging whether the condition is true , To decide which branch to take , Divided into single branches , Double branch , Multiple branches
Single branch selection structure ：
If Conditional expression ： # Logical expression , Relationship expression , Arithmetic expressions
sentence / Sentence block
Two branch selection structure ：
If Conditional expression ：
sentence / Sentence block
else：
sentence / Sentence block
Ternary conditional operators ：
Grammar format ： Value when condition is true if（ Conditional expression ）else The value when the condition is false
Num=input(‘ Please enter a number ：’)
print(Num if int(Num)<10 else ‘ The number is too big ’)
Multi branch selection structure ：
If Conditional expression 1：
sentence 1/ Sentence block 1
elif Conditional expression 2:
sentence 2/ Sentence block 2
.........
elif Conditional expression n:
sentence n/ Sentence block n
[else：
sentence n+1/ Sentence block n+1]
Select nesting of structure ：
The selection structure can be nested , Note the amount of indentation between different code blocks
While loop ：
While Conditional expression ：
Loop body statement
num=0
sum=0
while num<=100: # Calculation 1~100 And
sum+=num
num+=1
print(sum)
for Loop and iteratable object traversal ：
for Loops are usually useful for iterating over iteratible objects ：
for Variable in Iteratable object ：
Iteratable object
for i in range（5）：
print（i）
Ergodic dictionary ：
a = {'name': 'gaoqi', 'age': 18, 'job': 'student'}
for i in a:
for i in a.keys():
for i in a.values():
break sentence ：
stay while and for Use in loop break sentence , To end the cycle , When there are nested loops , You can only jump out of the loop of the nearest layer
continue sentence ：
continue Used to end this cycle , Go on for the next time , When multiple loops are nested , Apply to the most recent loop
else sentence ：
One can be attached to the loop else sentence （ Optional ）, If the loop statement is not break end , Will perform else sentence , Otherwise, do not execute
Loop code optimization ：
Minimize unnecessary calculations inside the loop
Nested loop , Minimize the calculation of inner circulation
Local variable query is faster , Try to use local variables
send zip（） Parallel iteration ：
We can go through zip() Function iterates over multiple functions in parallel , Iterations are stopped when the shortest sequence runs out
name = ('1', '2', '3', '4')
age = ('1', '2', '3', '4')
job = ('1', '2', '3')
for names, ages, jobs in zip(name, age, job):
print('{0}--{1}--{2}'.format(names, ages, jobs))
for i in range(3):
print('{0}--{1}--{2}'.format(name[i], age[i], job[i]))
Inferentially create sequences :
List objects are generated by list derivation ：
[ expression for item in Iteratable object if conditional ]
# You can use two loops , Use zip Parallel iteration
cells=[(row,col)for row,col in zip(range(1,10),range(101,110))]
for cell in cells:
print(cell)
Dictionary derivation ：
{key:value for expression in Iteratable object }
citys = [' Beijing ', ' Shanghai ', ' Shenzhen ', ' Guangzhou ']
s = {id * 100: city for id, city in zip(range(1, 5), citys)}
print(s)
Set derivation ：
{ expression for item in Iteratable object if conditional }
Generator derivation （ Do not generate tuples directly ）：
A generator can only run once , The first iteration can get the data , The second time the data is gone
（ expression for item in Iteratable object if conditional ）
Draw concentric circles of different colors ：
import turtle
p = turtle.Pen()
radius = [x * 10 for x in range(1, 11)]
p.width(4)
my_color = ('red', 'yellow', 'blue', 'black')
for r, i in zip(radius, range(len(radius))):
p.penup()
p.goto(0, -r)
p.pendown()
p.color(my_color[i % len(my_color)])
p.circle(r)
turtle.done()
author ：small_monsters
Game programming , A game development favorite ~
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