python的for，while及if

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python的迴圈及判斷認證賬戶和密碼

import getpass  #匯入模組username = input(‘username: ‘)password = getpass.getpass(‘password: ‘)  #輸入密碼不顯示使用者密碼認證：if及else# Author:Yao Xiaodongimport getpass_username = ‘Arthur‘_password = ‘123456‘ username = input(‘username: ‘)password = input(‘password: ‘) if _username == username and _password == password:    print(‘welcome {name} to python world‘.format(name=username))else:    print(‘auth filed‘)

猜測年齡while方式

#while迴圈authur_age = 500count = 0while count < 3:    guess_age = int(input(‘guess_age: ‘))    if guess_age == authur_age :        print(‘yes,you are right!‘)        break    elif guess_age > authur_age :        print(‘It is to bigger...‘)    else:        print(‘It is to smaller...‘)    count += 1else:    print(‘Error‘)

for方式

for迴圈authur_age = 500for i in range(3):    guess_age = int(input(‘guess_age: ‘))    if guess_age == Yxd_age :        print(‘yes,you are right!‘)        break    elif guess_age > Yxd_age :        print(‘It is to bigger...‘)    else:        print(‘It is to smaller...‘)else:    print(‘Error‘)

 while+if判斷三次後是否繼續

age = 21count = 0while count < 3:    guess_count = int(input("guess_count: "))    if guess_count == age:        print(‘yes‘)
        break
    elif guess_count > age:        print(‘big‘)    else:        print(‘small‘)    count += 1    if count == 3:        paly = input(‘do you want paly agen?(y/n): ‘)        if paly == ‘y‘:            count = 0        elif paly == ‘n‘:            print(‘all right‘)
        else:            print(‘(y/n)do you know?‘)

break和continue的有什麼不同？

不同點

break跳出整個迴圈，如果迴圈中遇到了break，那麼這個迴圈直接無效。

continue跳出當前迴圈，如果迴圈中遇到了continue，跳出本次迴圈繼續下次迴圈。

 

相同點：

break和continue都是只跳出當前迴圈，也就是說如果是for迴圈套for迴圈的時候，只會跳出break或者continue所在的那個for迴圈。舉個例子：

例如：

for i in range(3):    print(‘---------‘,i,‘-------‘)    for n in range(3):        if n > 1:            print(n)        else:            break#運行結果為--------- 0 ---------------- 1 ---------------- 2 -------
#也就是說遇到了break後整個迴圈都沒有了結果，但是外迴圈沒有影響

再看continue

for i in range(3):    print(‘---------‘,i,‘-------‘)    for n in range(3):        if n > 1:            print(n)        else:            continue#運行結果為--------- 0 -------2--------- 1 -------2--------- 2 -------2
#也就是說continue只是跳出一次迴圈，而不是整個迴圈，

但是外迴圈沒有影響

 

    

python的for，while及if