四 python 流程判断

1 if else 流程判断 强制缩进

_usename = ""

_password = ""

if _usename == username and _password == password:

　　print("welcome user {name} login ...".format(name==username))

else:

　　print ("invalid username or password")

父级代码顶格写,不能缩进

 

2 while 循环   while ... elif

count = 0

while True

　　print("count:" count)

　　count +=1

elif :

　　..........

else:

　　break