关于Python中的ifelse、while和for循环的简单小结

1.ifelse

1.1首先简单编辑一个关于ifelse的程序：

_username = ‘yanfeixu’

_password = ‘wuyifan’

username = input(“username:”)

password = input(“password:”)

print(username,password)

if _username == username and _password == password:

print(“Welcome user {name} login…”.format(name=username))

else:

print(“Invalid username or password!”)

# getpass可以使密码变成密文，但是在pycharm中不方便使用

#username = input(“username:”)

#password = getpass.getpass(“password:”)

#print(username,password)

1.2.当设计到三个选项的时候，就要利用到elif

if guess_age == age_of_oldboy:

print(“yes,you got it.”)

elif guess_age > age_of_oldboy:

print(“think smaller…”)

else:

print(“think bigger!”)

2.while

age_of_oldboy = 56

count = 0

while True: # 可以利用循环，不会只执行一次就退出 # if count == 3: # 执行三次就退出 # break

while count < 3: # 和上面的三行注释是一样的效果

guess_age = int(input(“guess age:”))

if guess_age == age_of_oldboy:

print(“yes,you got it.”)

break

elif guess_age > age_of_oldboy:

print(“think smaller…”)

else:

print(“think bigger!”)

count += 1

else:

print(“you have tries too much times…”)

3.for

age_of_oldboy = 56

for i in range(3): # 循环的第二种表示方法for

guess_age = int(input(“guess age:”))

if guess_age == age_of_oldboy:

print(“yes,you got it.”)

break

elif guess_age > age_of_oldboy:

print(“think smaller…”)

else:

print(“think bigger!”)

else:

print(“you have tries too much times…”)

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