python --003--流程控制while,for
順序流程:每一行代碼都會執行,並且只會執行一次
···
if -- else 結構語句:
1、if 布爾表達式:
代碼對齊,tab與空格不能夠同時出現
2、if 布爾表達式:
代碼
else:
money = input (‘please input your money:‘)
if money > 100:
print ‘you are vip!‘
print ‘you are gold VIP‘
else :
print(‘you are not vip!‘)
3、if--else 嵌套:
if 布爾表達式:
代碼
else:
if 布爾表達式:
代碼
else:
代碼
....
money = input (‘please input your money:‘)
print ‘you are vip!‘
if money >= 200:
print ‘you are golden VIP‘
if 200>money>100:
print‘you are silver vip‘
else :
if money<0:
print‘error!‘
else:
print(‘you are not vip!‘)
4、if 布爾表達式:
代碼
elif 布爾表達式:
代碼
money = input (‘please input your money:‘)
if money > 100:
print ‘you are vip!‘
if money >= 200:
if 200>money>100:
print‘you are silver vip‘
elif money<0:
print‘error!‘
else:
print(‘you are not vip!‘)
EG:
第一種:
#coding:UTF-8
score = int(input(‘please input a score:‘))
if 100>=score>=90:
print(‘很好‘)
if 90>=score>=70:
print(‘well done!‘)
if 70>=score>=60:
print(‘pass!‘)
print(‘failed!‘)
if score>100 or score<0:
print (‘error!‘)
第二種:
-- coding: cp936 --
score = int(input(‘please input a score:‘))
if 100>=score>=90:
print(‘很好‘)
else:
if 90>=score>=70:
print(‘良好‘)
else:
if 70>=score>=60:
print(‘及格‘)
else:
if 60>score>=0:
print(‘不及格‘)
else:
print (‘error!‘)
第三種:
score = int(input(‘your number:‘))
if 100>=score>=90:
print(‘excellent‘)
elif 90>=score>=70:
print(‘good‘)
elif 70>=score>=60:
print(‘pass‘)
elif 60>score>=0:
print(‘flunk‘)
else:
print (‘error!‘)
循環流程
··while 循環
重復運行某些代碼
1、語法:
while 布爾表達式:
代碼:(循環體)
註意:要避免死循環(註意循環跳出條件)
服務器就是死循環724365
num = 0
while num<10:
print ‘hello world!‘
num+=1
·····for循環
1、語法:
for 目標 in 表達式:
循環體
目標:變量
表達式:字符串、列表、元祖----可叠代對象
a = ‘baizhi‘
for i in a:
print i
teacher = [‘fei‘,‘xige‘,‘kuai‘]
for i in teacher:
print i
number = [123,466,969]
for i in number:
print i
·range()
語法:
range([start],stop[,step=1])
1、這個函數有三個參數,其中方括號表示可選擇參數()
2、第一個參數默認就是0,第二個參數停止,第三默認1
3、作用生成一個值,從start開始,到stop結束的數字序列
取值範圍從[start,stop)左閉右開
a = range(0,3,1)
>> a
[0, 1, 2]
>>
>> a=range(0,10,2)
>> a
[0, 2, 4, 6, 8]
>> a = range(0,10,3)
>> a
[0, 3, 6, 9]
>> range(3)
[0, 1, 2]
for i in range(5):
print i
01
2
3
4
>> for i in range(2,5):
print i
2
3
4
>> for i in range(1,5,2):
print i
1
3
··break
跳出當前循環,後面所有循環都不執行
while True:
num = input(‘please input your number:‘)
if num ==1:
break
print(‘error,try again!‘)
please input your number:3
error,try again!
please input your number:1
·continue
跳過本次循環,不影響下次循環
for i in range(10):
if i%2!=0:
continue
print i
02
4
6
8
>> for i in range(10):
if i%2!=0:
break
print i
python --003--流程控制while,for