python——if判断语句和逻辑运算符

一、if 判断语句

1、if判断语句

if 要判断的条件(True): 条件成立的时候，要做的事情 else: 条件不成立的时候要做的事情 或者是 if <判断条件1> ： <条件1成立要执行的语句> if <判断条件2> ： <条件2成立要执行的语句> else ： <条件都不成立要执行的语句>

[root@localhost mnt]# vim age.py [root@localhost mnt]# cat age.py age = 17 if age >= 18: print('you are too old ') else: print('you are too young') [root@localhost mnt]# /usr/local/python3/bin/python3 age.py you are too young [root@localhost mnt]#

2、elif判断

if 要判断的条件(True): 条件成立的时候，要做的事情 elif 要判断的条件(True): … elif 要判断的条件(True): … else: 条件不成立的时候要做的事情

grade = 90 if grade > 90 : print ('your chengji is: A') elif grade ==90: print ('your chengji is : B') else: print ('your chengji is :C') print(grade)

3、if 判断是否为空

二、逻辑运算符

and 条件1 and 条件2 两个条件同时满足，就返回True 只要有一个条件不满足，就返回False or 条件1 or 条件2 两个条件只要有一个满足，就返回True 两个条件都不满足的时候，就返回False

代码展示

[root@localhost mnt]# vim tongguo.py [root@localhost mnt]# cat tongguo.py python_source = 80 c_source = 70 if python_source >= 60 or c_source >=50: print('exam is pass') else: print('working hard')

效果展示

[root@localhost mnt]# /usr/local/python3/bin/python3 tongguo.py exam is pass

random.randint(start，stop) 生成一个范围内的随机数

代码

[root@localhost mnt]# vim suiji.py [root@localhost mnt]# cat suiji.py user = float(input('please put a Num:')) import random computer = random.randint(0,999) if user > computer: print('more bigger') elif user == computer: print('the equal') else: print('so little')

效果展示

[root@localhost mnt]# /usr/local/python3/bin/python3 suiji.py please put a Num:88 so little

三、 if 案例展示

需求： # 1.从控制台输入要出的拳 ---石头(1)/剪刀(2)/布(3) # 2.电脑随即出拳 # 3.比较胜负 # 石头 胜 剪刀 # 剪刀 胜 布 # 布 胜 石头

代码

[root@localhost mnt]# vim shitou.py [root@localhost mnt]# cat shitou.py player = int(input('please a put a shuzhi:----shitou(1) jiandao(2) bu(3)')) import random computer = random.randint(1,3) if ((player ==1 and computer == 2) or (player ==2 and computer == 3) or (player ==3 and computer == 1)): print('wanjia is win') elif ( player == computer ): print('pingju') else: print('wanjia is defabet')

效果展示

[root@localhost mnt]# /usr/local/python3/bin/python3 shitou.py please a put a shuzhi:----shitou(1) jiandao(2) bu(3)2 wanjia is win

判断闰年?

用户输入年份year, 判断是否为闰年?

year能被4整除但是不能被100整除 或者 year能被400整除, 那么就是闰年; 代码 [root@localhost mnt]# vim runnian.py [root@localhost mnt]# cat runnian.py year=int(input('please put year:')) if ((year%4==0 and year0!=0) or (year@0==0)): print('is runyear') else: print('not runyear')

效果展示

[root@localhost mnt]# /usr/local/python3/bin/python3 runnian.py please put year:2019 not runyear [root@localhost mnt]# /usr/local/python3/bin/python3 runnian.py please put year:2008 is runyear

输入年、月，输出本月有多少天。合理选择分支语句完成设计任务。

[root@localhost mnt]# vim nianyue.py [root@localhost mnt]# cat nianyue.py year = int(input('please put year: ')) month = int(input('please put month:')) if month==1 or month==3 or month==5 or month==7 or month==8 or month==10 or month==12: print('this month have 31days') elif month==4 or month==6 or month==9 or month==11: print('this month have 30days') else: if ((year%4==0 and year0!=0) or (year@0==0)): print('this month have 29days') else: print('this month have 28days') [root@localhost mnt]#

效果展示

[root@localhost mnt]# /usr/local/python3/bin/python3 nianyue.py please put year: 2018 please put month:3 this month have 31days [root@localhost mnt]# /usr/local/python3/bin/python3 runnian.py please put year:2008 is runyear [root@localhost mnt]# /usr/local/python3/bin/python3 nianyue.py please put year: 2008 please put month:2 this month have 29days [root@localhost mnt]#

3. 根据用于指定月份，打印该月份所属的季节。

提示: 3,4,5 春季 6,7,8 夏季 9,10,11 秋季 12, 1, 2 冬季

[root@localhost mnt]# vim jijie.py [root@localhost mnt]# cat jijie.py month = int(input('please put a Num: ')) if month==3 or month==4 or month==5: print('chunji') elif month==6 or month==7 or month==8: print('xiaji') elif month==9 or month==10 or month==11: print('qiuji') elif month==12 or month==1 or month==2: print('dongji')

效果展示

[root@localhost mnt]# /usr/local/python3/bin/python3 jijie.py please put a Num: 5 chunji [root@localhost mnt]# /usr/local/python3/bin/python3 jijie.py please put a Num: 9 qiuji