Study 7 —— while循環停止語句

循環的終止語句
break 　　 #用於徹底結束一個循環，跳出循環體執行循環後面的語句
continue 　　 #只終止本次循環，接着執行後面的循環

1. 打印0-100，截止到第6次

count = 0
while count <= 100:
    print('Value: ', count)
　　if count == 5:
	　　break
　　count += 1

2. 打印0-100，截止到第6次，第6次無限循環打印

count = 0
while count <= 100:
    print('Value: ', count)
    if count == 5:
	　　continue
    count += 1

3. 打印1-5，95-101

count = 0
while count <= 100:
    count += 1
    if count > 5 and count < 95:
	　　continue
    print('Value: ', count)

4. 猜年齡，容許用戶猜三次，中間猜對跳出循環

count = 0
age =18

while count < 3:
    user_guess = int(input('Input Number: '))
    if user_guess == age:
	　　print('Yes, you are right!')
	　　break
    elif user_guess > age:
	　　print('Try smaller!')
    else:
	　　print('Try bigger!')

    count += 1

5. 猜年齡，容許用戶猜三次，中間猜對跳出循環，猜了三次後若沒有猜對，詢問是否繼續，Y則繼續，N則結束

count = 0
age =18

while count < 3:
    user_guess = int(input('Input Number: '))
    if user_guess == age:
	　　print('Yes, you are right!')
	　　break
    　　elif user_guess > age:
	　　　　print('Try smaller!')
    　　else:
	　　　　print('Try bigger!')
    　　count += 1

    if count == 3:
	　　choice = input('Whether or not to continue?(Y/N): ')
	　　if choice == 'Y' or choice == 'y':
	    　　count = 0
	　　elif choice == 'N' or choice == 'n':
	    　　pass
	　　else:
	    　　print('You must input Y/y or N/n !')
	    　　pass

6. 賬號密碼判斷

ACCOUNT = 'yancy'
PASSWD = '123!'

count = 0

while count < 1:
    account = input('Enter your account: ')
    passwd = input('Enter your password: ')

    if account == ACCOUNT and passwd == PASSWD:
        print('Welcome to the sso system!')
        break
    elif account == ACCOUNT and passwd != PASSWD:
        print('Your password is wrong!')
    elif account != ACCOUNT:
        print("Your account doesn't exist!")
    count += 1

    if count == 1:
        while True:
            choice = input('Whether not continue?(Y/N): ')
            if choice == 'Y' or choice == 'y':
                count = 0
                break
            elif choice == 'N' or choice == 'n':
                print('You quit the program!')
                break
            else:
                print("You must enter 'Y/y' or 'N/n'!")
                continue

 

while ... else語法

當while循環正常執行完畢，中間沒有被break停止，就會執行else後面的語句

count = 0
while count <= 100:
    print('Value: ', count)
    if count == 5:
	　　break       #有break時，else下面的內容就不打印，沒有break時，就打印。
    count += 1
else：
    print('loop is done.')

else語法可用於判斷while程序中間是否被break中斷跳出