算术运算符与赋值运算符
#1. 算术运算 # print(10 / 3) # print(10 // 3) # print(10 ** 2) #2. 赋值运算 # 增量赋值 # age=18 # age+=1#age=age + 1 # print(age) # age=18 # age/=3 #age=age/3 # print(type(age)) # age**=2 #age=age**2 # 交叉赋值 # x=10 # y=20 # # # temp=x # # x=y # # y=temp # x,y=y,x # print(x,y) # 链式赋值 # x=10 # y=x # z=y # x=y=z=10 # # print(id(x)) # print(id(y)) # print(id(z)) # 解压赋值 l=[1.2,2.2,3.3,4.4,5.5] # a=l[0] # b=l[1] # c=l[2] # d=l[3] # e=l[4] # a,b,c,d,e=l # a,b,c,d,e,f=l # a,b,c,d=l # print(a,b,c,d,e) # l=[1.2,2.2,3.3,4.4,5.5] # a,b,*_=l # print(a,b) # a,*_,b=l # print(a,b) # *_,a,b=l # print(a,b)
流程控制之if判断
''' 语法1: if 条件: 代码1 代码2 代码3 ... ''' # age_of_bk=30 # print('start.....') # # inp_age=input('>>>: ') #inp_age='18' # inp_age=int(inp_age) # if inp_age == age_of_bk: # print('猜对了') # # print('end.....') ''' 语法2: if 条件: 代码1 代码2 代码3 ... else: 代码1 代码2 代码3 ... ''' # age=38 # gender='male' # is_beautiful=True # # if age >= 18 and age <= 25 and gender == 'female' and is_beautiful: # print('开始表白。。。。') # # else: # print('阿姨好') # ''' 语法3: if 条件1: 代码1 代码2 代码3 ... elif 条件2: 代码1 代码2 代码3 ... elif 条件3: 代码1 代码2 代码3 ... elif 条件4: 代码1 代码2 代码3 ... else: 代码1 代码2 代码3 ... ''' ''' 如果: 成绩>=90,那么:优秀 如果成绩>=80且<90,那么:良好 如果成绩>=70且<80,那么:普通 其他情况:很差 ''' # score=input('your score>>: ') # score=int(score) # if score >=90: # print('优秀') # elif score >=80: # print('良好') # elif score >=70: # print('普通') # else: # print('很差') # if 条件1: # 代码1 # 代码2 # 代码3 # if 条件2: # 代码1 # 代码2 # 代码3 ''' 语法4: if 条件1: if 条件2: 代码1 代码2 代码3 ... 代码2 代码3 ''' age=18 gender='female' is_beautiful=True is_successful=True if age >= 18 and age <= 25 and gender == 'female' and is_beautiful: print('开始表白。。。。') if is_successful: print('在一起') else: print('我逗你玩呢。。。') else: print('阿姨好')
流程控制之while循环
#1. while循环:条件循环 # I: 基本语法 # while 条件: # 代码1 # 代码2 # 代码3 # ... # 示范 # name_of_bk='egon' # pwd_of_bk='123' # # tag=True # while tag: # inp_name=input('your name>>: ') # inp_pwd=input('your password>>: ') # if inp_name == name_of_bk and inp_pwd == pwd_of_bk: # print('login successful') # tag=False # else: # print('username or password error') # # print('other code...') # II: while+break:break代表结束本层循环 # 示范: # while True: # print(1) # break # print(2) # print(3) # name_of_bk='egon' # pwd_of_bk='123' # # while True: # inp_name=input('your name>>: ') # inp_pwd=input('your password>>: ') # if inp_name == name_of_bk and inp_pwd == pwd_of_bk: # print('login successful') # break # else: # print('username or password error') # # print('other code......') # III: while + continue: continue代表结束本次循环,直接进入下一次 # 示范 # count=1 # while count < 6: # if count == 3: # count+=1 # continue # print(count) # count+=1 # 输错三次退出 # name_of_bk='egon' # pwd_of_bk='123' # # count=0 # while True: # if count == 3: # print('输错的次数过多。。。') # break # inp_name=input('your name>>: ') # inp_pwd=input('your password>>: ') # if inp_name == name_of_bk and inp_pwd == pwd_of_bk: # print('login successful') # break # else: # print('username or password error') # count+=1 #count=3 输错3次 # IV:while + else # count=0 # while True: # if count == 10: # break # print(count) # count+=1 # # else: # print("else的子代块只有在while循环没有被break打断的情况下才会执行") # count=0 # while count <= 10: # print(count) # count+=1 # # else: # print("else的子代块只有在while循环没有被break打断的情况下才会执行") name_of_bk='egon' pwd_of_bk='123' count=0 tag=True while tag: if count == 3: print('输错的次数过多。。。') break inp_name=input('your name>>: ') inp_pwd=input('your password>>: ') if inp_name == name_of_bk and inp_pwd == pwd_of_bk: print('login successful') while tag: print(""" 0 退出 1 购物 2 支付 3 查看购物 """) cmd=input('>>>: ') if cmd == '0': tag=False continue if cmd == '1': print('购物。。。。。。。') elif cmd == '2': print('支付。。。。。') elif cmd == '3': print('查看购物车') else: print('输入错误的指令') else: print('username or password error') count+=1 #count=3 输错3次 #2. for循环