20170417if.else条件控制

Posted 2020-09-11 云ime

1.条件判断

即：如果条件成立，就......；反之，就.......　　

def account_login():#定义函数，不需要参数
    password = input(\'Password:\')#用input获得用户输入的字符串并储存在变量password中
    if password ==\'12345\':
        print(\'Login success!\')#设置条件
    else:
        print(\'Wrong password or invalid input!\')
        account_login()#输入错误情况时，再次调用函数
account_login()#调用函数

当if后的表达式过长时，可以采取给变量赋值的办法

password_correct = password == \'12345\'

if password_correct: #此时password_correct的值为1/0

#判断学生成绩

while True:
    grade = int(input(\'请输入你的分数\'))
    if 100 >= grade >= 90:
        print(\'A\')
    elif 90 > grade >= 80:
        print(\'B\')
    elif 80 > grade >= 70:
        print(\'C\')
    elif 70 > grade >= 60:
        print(\'D\')
    elif grade < 0 or grade > 100:
        print(\'输入错误\')
    else:
        print(\'E\')

2.多条件判断

 

password_list = [\'*\',\'12345\']
def account_login():
    password = input(\'Password:\')
    password_correct = password == password_list[-1]
    password_reset = password == password_list[0]
    if password_correct:
        print(\'Login success!\')
    elif password_reset:
        new_password = input(\'Enter a new password:\')
        password_list.append(new_password)
        print(\'Your password has changed successfully!\')
        account_login()
    else:
        print(\'Wrong password or invalid input!\')
        account_login()
account_login()