python_条件循环判断(break&continue&import&input)
循环=迭代=遍历
if 条件判断(变量赋值、input接收的均为字符串):
#input 接收到的输入为字符串,所以如果需要对比大小需要先转换类型 score=input('请输入您的成绩:') score=int(score) if score>90: print('优秀') elif score>80: print('良') elif score>=60: print('及格') else: print('不及格')
while条件循环(循环、迭代、遍历):
须提前定义计数,否则为死循环直至py报错
count=0 while count<3: print('哈哈') count += 1
循环中break和continue的区别案例:
# 代码1:
count=0
while count<10:
if count==3:
break
print('哈哈')
count+=1
# 代码2: count=0 while count<10: print('哈哈') count+=1 if count==3: break
代码1和代码2的效果一样,皆打印三行哈哈
for循环:(数组list循环)
money=200 names=['xiaohong','xiaoming','xiaolan','xiaobai'] for name in names: if name=='xiaoming': continue print('给%s发%s元钱'%(name,money))
import导入模块
import random num=random.randint(1,1000)#随机产生一个整数 print(num) count=0 while count <3: count+=1 guess=int(input('请输入您猜的数字:')) if guess>num: print('猜大了') elif guess<num: print('猜小了') else: print('恭喜您,猜对了!游戏结束') break else: print('次数已用尽,游戏结束') # 正常结束while循环,会执行else代码;如果是break结束的循环,则不会执行else
用户登录校验:
usernames=['xiaoming','xiaohong','xiaolan'] passwords=['123456','abc123','1234@qwer'] import datetime today=datetime.datetime.today() for i in range(3): username=input('username:').strip() password=input('password:') password=password.strip()#去掉字符串两边的空格 if username=='' or password=='': print('账号/密码不能为空!') # elif usernames.count(username)==0:判断元素的个数 elif username not in usernames:#判断远古三是否在list中 print('用户不存在!') else: user_index=usernames.index(username) p=passwords[user_index] if password==p: print('欢迎%s登录,今天的日期是%s。'%(username,today)) break else: print('密码错误!') else: print('次数已用尽!')