python-条件判断
条件判断
运算符
1.比较运算符 : == != <= >= < >
2.算术运算符: + - * / %
3.赋值运算符: += -= *= /=
4.逻辑运算符: and or not 两个表达式进行判断
and:两个条件都为真 x==y and x<z
or:两个表达是有一个为真
not:表达式为真 假
a=1
b=2
print(not a==b)
5.成员运算符:in not in
6.身份运算符: is not is 判断同一个对象
""" if 条件: 条件满足的事情: else: 不满足的事情 """ age = int(input('请输入年龄:')) if age >= 18: print("可以上网") else: print("回家学习") list1 = [1, 3, 'q',233] if 1 in list1: print('在列表中') else: print('不在列表中')
多重if:
name = input("请输入名字:") if name in '虚竹': print('打一顿') elif name in '二狗': print('wangwang') elif name in 'mm': print('mmmmm') else: print('没有这个名字')
if 嵌套
""" if 条件: if 条件: print('xxx') elif 条件: print('xxx') else: print('xxx') else: 执行不满足条件 """ # 判断成绩 grade = int(input('输入成绩:')) if grade >= 70: if grade >= 80: print('吃糖') else: print('吃肉') else: print('喝粥') import random player = int(input('请输入一个数字:')) computer = random.randint(1,3) print('玩家输出的是:%s,电脑输出的是:%s'%(player,computer)) if(player==2 and computer==3)or(player==1 and computer ==2) or (player==3 and computer==1): print('玩家赢') elif (player==computer): print('平局') else: print('电脑输')
循环:重复执行 while for
''' while 条件: 循环内容 ''' i=0 sum = 0 while i<=100: print(i) sum = sum+i i+=1 if i ==101: print('o到100求和:%s'%sum)
循环中的break,continue 退出循环
break 当某一条件满足退出循环,整个循环
continue 当某一条件满足的时候,退出循环,本次循环
i=0 while i<=10: print(i) if i ==3: break i+=1 continue i=0 while i<=10: print(i) if i ==3: i+=1 continue i+=1
嵌套循环
row=1 while row<=5: cols =1 while cols<row: print('*',end='') cols +=1 print('*') row +=1 ''' 循环完了,执行的代码 while 条件: 循环语句 else: 语句 ''' # 循环结束就不会执行else i=0 while i<=10: print(i) if i ==3: break i+=1 else: print('循环完了') ''' for 变量名 in 区间/列表: 循环体 ''' # 循环5次 for i in range(5): # range:左闭右开的区间 print('hello world') # 循环列表 list1 = ['xiaomu', 'xiaoming', 3] for i in list1: print(i) # 循环字典 dict1 = {'a':'1','b':'3'} for i in dict1: print(i+':'+dict1[i]) row = 0 for row in range(5): if row < 5: j = 0 for j in range(5): if j < row: print('*', end='') j += 1 print('*') row += 1
# sum1 = 0 for i in range(1,101): print(i) if i <= 100: sum1 = sum1 + i i += 1 print('1到%s的和:%s' % (i, sum1))