!!! Statement!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1. code example: #if语句
#!/usr/bin/python3
#_ *_coding:utf-8_*_
num = 10
if num = = 10:
Print (' pair ')
Operation Result:
[email protected] ~]# python if.py
Right
2. Complex if statement #注意事项: Be sure to pay attention to the Chinese and English format, statement indentation, indentation for 4 spaces, remember!!!
Code instance: if statement
#!/usr/bin/python3
#_ *_coding:utf-8_*_
XGJ = ' HTUIDC '
if xgj = = ' HTUIDC ':
xuesheng={' QQQ ': ' 1001 ', ' wwww ': ' 1002 ', ' eee ': ' 1003 '}
Print (' Number of dictionary elements:%d '%len (Xuesheng) ')
Xuesheng.clear ()
Print (' Number of elements after dictionary deletion:%d '%len (Xuesheng))
Operation Result:
Number of dictionary elements: 3
Number of elements after dictionary deletion: 0
3.else Statement #我理解的else的意思是 Otherwise, if how what happens otherwise else what happens, else is not a standalone statement, only as part of the IF statement.
code example:
#!/usr/bin/python3
#_ *_coding:utf-8_*_
num = 10
If num > 10:
Print (' wrong ')
Else
Print (' other ')
Operation Result:
Other
A 4.elif statement #elif是else与if的简写, meaning the conditional else statement, which needs to be judged again.
code example:
#!/usr/bin/python3
#_ *_coding:utf-8_*_
num = 10
If num > 10:
Print (' wrong ')
elif 0 <= Num >=10:
Print (' In an interval ')
Else
Print (' other ')
Operation Result:
In an interval
Nested code blocks
code example:
#!/usr/bin/env Python3
#!/-*-coding-utf-8-*-
num = 10
If num%2==0:
If num%3==0:
Print (' The number you enter can be divisible by 2 and 3 ')
Elif num%4==0:
Print (' The number you enter can be divisible by 2 and 4 ')
Else
Print (' The number you enter can be divisible by 2, but not divisible by 3 and 4 ')
Else
If num%3==0:
Print (' The number you enter can be divisible by 3, but not divisible by 2 ')
Else
Print (' The number you entered cannot be divisible by 2 and 3 ')
Operation Result:
The number you enter can be divisible by 2, but not divisible by 3 and 4.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
is identity operator
>>> x=y=[1,2]
>>> z=[1,2]
>>> x==y
True
>>> x==z
True
>>> y==z
True
>>> x is y
True
>>> X is Z
False
# # #虽然值相同, but not in an object
>>> x is not Z
True
!!!!!! Cycle!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1.while Cycle
code example:
#!/usr/bin/python3
#!_*_coding:utf-8_*_
N=1
While n<=1000:
Print (' Current number is: ', n ')
N +=1
Operation Result:
The current number is: 1
The current number is: 2
The current number is: ...
The current number is: 999
The current number is: 1000
2.for Cycle
code example:
#!/usr/bin/python3
#!-*-coding:utf-8-*-
N=0 #进行赋值
Fields=[' A ', ' B ', ' C '] #进行赋值
While N<len (fields): #条件判断---If n is less than the length of the fields
Print (Fields[n]) #打印fields的0索引位置
N+=1 #加法赋值运算符 n=n+1
Operation Result:
A
B
C
code example:
htuidc=[' 1 ', ' 2 ', ' 3 '] #赋值
For DL in HTUIDC: #for in loop printing
Print (DL) #进行打印
Operation Result:
1
2
3
# # #注意事项: If you can use a for loop, try not to use the WHILE loop!!!
!!! Iterative TOOLS!!!!!
1. Parallel iterations
code example:
#!/usr/bin/python3
#!-*-coding:utf-8-*-
student1=[' qqq ', ' www ', ' eee ']
NUMBER=[1001,1002,1003]
For I in range (len (student1)):
Print (Number[i])
htu=[' d ', ' l ']
IDC=[1001,1002,1003]
For XGJ,DH in Zip (HTU,IDC):
Print (XGJ)
xgj=[' 1 ', ' 2 ']
DH=[1001,1002]
For HTU,IDC in Zip (XGJ,DH):
Print (IDC)
Operation Result:
1001
1002
1003
D
L
1001
1002
# # #注意: The ZIP function can act on any number of sequences.
!!!!!!! Jump out of the loop!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1.break statements are used in the while and for loops
code example:
#!/usr/bin/python3
#!/-*-coding:utf-8-*-
For letter in ' Hello ':
If letter = = ' L ': #遍历打印, know loop print to L bounce loop
Break
Print (' Current letters: ', letter)
num = 10
While num > 0:
Print (' Output number: ', num)
num-= 1
if num = = 8: #遍历打印输出, know equals 8 jumps out of the loop
Break
Operation Result:
The current letter is: H
The current letter is: E
Output numbers are: 10
Output numbers are: 9
2.continue #跳出当前的循环, then the next round of the loop----can only jump out once
code example:
#!/usr/bin/python3
#!/-*-coding:utf-8-*-
For letter in ' Hello ':
If letter = = ' L ': #遍历打印, know loop print to L bounce loop, then out L resume print loop
Continue
Print (' Current letters: ', letter)
Operation Result:
H
E
O
Else clause in a loop
1. Using else in while
code example:
num = 0
While num < 3:
Print (num, ' less than 3 ')
num = num + 1
Else
Print (num, ' greater than or equal to 3 ')
Print (' End Loop ')
Operation Result:
0 less than 3
1 less than 3
2 Less than 3
3 is greater than or equal to 3
End Loop
2. Using else in for
code example:
#!/usr/bin/python3
#!/-*-coding:utf-8-*-
names = [' Xiaomeng ', ' Xiaozhi ']
For name in Names:
If name = = ' Xiao ':
Print (' name: ', name)
Break
Print (' Circular Name list ' +name)
Else
Print (' No looping data ')
Print (' End Loop ')
Operation Result:
Circular Name List Xiaomeng
Circular Name List Xiaozhi
No cyclic data
End Loop
!!! PASS STATEMENT!!!!!!
Pass is an empty statement #就是什么都不做的语句, only a placeholder statement.
#!/usr/bin/python3
#!/-*-coding:utf-8-*-
XGJ = ' HTUIDC '
if xgj = = ' HTUIDC ':
Print (' pair ')
elif Xgj = = ' Idchtu ':
Pass # # #如果没有这个占位语句就会出错
Else
Print (' wrong ')
Operation Result:
Right
To be Continued ... This chapter is chapter II
Follow-up continue chapter III
Two, the Python foundation---loop--condition judgment (while-for-if-elif-else)