while迴圈實現使用者登入

_user = "tom"
_passwd = "abc123"

counter = 0
while counter < 3:  　　#當條件為假時，跳出迴圈
    username = input("Username:")
    password = input("Password:")
    if username == _user and password == _passwd:
        print("welcome %s login...." % _user)
        break           # 跳出迴圈
    else
 
:
        print("Invalid username or password!")
    counter += 1
    if counter == 3:
        keeping_going = input("還想繼續嗎？[Y/N]")
        if keeping_going == "Y":
            counter = 0

else:
    print("已經錯三次了，雙雙小可愛") 

continue和break：

continue   # 結束本次迴圈，進行下次迴圈

Break      # 跳出整個當前迴圈

例項程式：

exit_flag = False

for n in range(10):
    if n < 5:
        continue
    print(n)
    for N in range(10):
        print("layer2", N)
        if N == 6:
            exit_flag = True
            break
    if exit_flag:
 　　　　break

 輸出結果：