day05_05 for循环、break语句

_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")

for i in range(3):
    print(i)

输出结果

0
1
2

以下代码只能在python2.x才能看出来

for i in range(3):
    print("loop:",i)

　　输出结果

loop: 0
loop: 1
loop: 2

规律:前包后不包

打印1-100的所有奇数

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

　　方法二:

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

　　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)

　　方法二:

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

　　最多输入3次的案例

for i in range(3):
    username = input("Username:")
    password = input("Password:")
    if username == _user and password == _passwd:
        print("Welcome %s login..." %_user)
        break
    else:
        print("Invalid username or password")