day05_05 for循环、break语句

1.0 输入用户名,密码练习

_user = "alex"
_passwd = "abc123"
 
username = input("Username:")
password = input("Password:")
 
if username == _user and password == _passwd:
    print("Welcome %s login..." %_user)
else:
    print("Invalid username or password")
#>>>Username:alex
#>>>Password:abc123
#>>>Welcome alex login...

2.0 循环0-3(不包括3的数字)

for i in range(3):
    print(i)
#>>>0
#>>>1
#>>>2

3.0 以下命令只能在python2.x模式下才能显示

>>>range(3)
[0,1,2]

4.0 for案例

for i in range(3):
    print("loop:",i)
    #>>>loop:0
    #>>>loop:1
    #>>>loop:2

3.1 range测试,只适用于python2.x版本中(规律:前包后不包)

>>> range(1,3)
[1,2]
 
>>>range(1,4)
[1,2,3]
 
>>>range(2,5)
[2,3,4]

5.0 打印1-100的所有奇数

for i in range(1,101):
    if i%2 == 1:
        print("loop:",i)

5.1 方法二:

for i in range(1,101,2):
        print("loop:",i)

5.2 打印1-100的数字,50-70不打印

for i in range(1,101):
    if i>=50 and i<=70 :
        continue;
    print(i)

5.2.2 方法二

for i in range(1,101):
    if i<50 or i>70 :
        print(i)

5.3 最多输入3次的案例

username_y = 'alex'
password_y = 'abc123'
for i in range(3):
    username = input("Username:")
    password = input("Password:")
    if username == username_y and password == password_y:
        print("Welcome %s login..." %username)
        break
    else:
        print("Invalid username or password")