python学习随笔2：python判断和循环

1.if-else

_username = 'heyue'
_password = ''

username = input("username:")
password = input("password:")

if username == _username and password == _password:
    print("welcome user {name} login...".format(name=_username))
else:
    print("invalid username or password")

2.if-elif-else

_age = 56
age = int(input("guess age:"))
if age == _age:
    print("you got it")
elif age > _age:
    print("think bigger")
else:
    print("think smaller")

3.while  最多猜三次

_age = 56
count = 0
while count < 3:
    age = int(input("guess age:"))
    if age == _age:
        print("you got it")
        break
    elif age > _age:
        print("think bigger")
    else:
        print("think smaller")
    count +=1
else:
    print("you have tried too much times...")

4. for 最多猜三次

_age = 56
for i in range(3):
    age = int(input("guess age:"))
    if age == _age:
        print("you got it")
        break
    elif age > _age:
        print("think bigger")
    else:
        print("think smaller")
else:
    print("you have tried too much times...")

5.猜三次后询问是否继续

_age = 56
count = 0
while count < 3:
    age = int(input("guess age:"))
    if age == _age:
        print("you got it")
        break
    elif age > _age:
        print("think bigger")
    else:
        print("think smaller")
    count +=1
    if count == 3:
        countinue_confirm = input("do you want to keep guessing...")
        if countinue_confirm != 'n':
            count = 0