1 # 分支、循环、条件与枚举 2 # 表达式(Expression)是运算符(operator)和操作数(operand)所构成的序列 3 a = 1 4 b = 2 5 c = 3 6 print(a + b * c, 1 or 2, 1 and 3, a or (b and c), (a or b) and c) # 7 1 3 1 3 a or b and c 从左向右(and优先级高于or) 7 print(not a or b + 2 == c) # False not a or b +2 == c 等价于 (not a) or ((b+2) == c) 8 print() 9 # 流程控制语句 10 ''' 11 多行注释 12 条件控制 循环控制 分支 13 if else for while switch 14 ''' 15 mood = False 16 if mood: 17 print('go to left') 18 else: 19 print('go to right') 20 21 a = 1 22 b = 2 23 if a > b: 24 print('go to left') 25 else: 26 print('go to right') 27 28 d = [] 29 if d: 30 print('go to left') 31 else: 32 print('go to right') 33 34 """ 35 模块注释:使用if else语句 模拟登录流程 36 """ 37 account = 'admin' 38 password = '123456' 39 print("please input account") 40 user_account = 'admin' #input() 41 print("please input password") 42 user_password = '123456' #input() 43 44 if user_account == account and user_password == password: 45 print("success") 46 else: 47 print("fail") 48 # constant常量 49 """ 50 if else 语句 51 52 pass 空语句(占位语句)保持语句的完整性 53 54 """ 55 code = True 56 if code: 57 pass 58 else: 59 pass 60 #if 可以单独使用 61 if True: 62 pass #空语句(占位语句)保持语句的完整性 63 if False: 64 pass 65 #if 嵌套使用 66 if True: 67 if True: 68 pass 69 else: 70 pass 71 else: 72 if False: 73 pass 74 else: 75 pass 76 """ 77 类表达式 78 79 class biaodashi(object): 80 pass 81 82 函数表达式(静态方法) 83 84 @staticmethod 85 def funcname(parameter_list): 86 pass 87 88 """ 89 """ 90 a = x 91 a = 1 print('apple') 92 a = 2 print('orange') 93 a = 3 print('banana') 94 print('shopping') 95 96 """ 97 a = 1 # int(input()) 98 if a == 1: 99 print('apple') 100 else: 101 if a == 2: 102 print('orange') 103 else: 104 if a == 3: 105 print('banana') 106 else: 107 print('shopping') 108 109 #代码改写 elif用法(简化代码、简化行数) 110 if a == 1: 111 print('apple') 112 elif a == 2: 113 print('orange') 114 elif a == 3: 115 print('banana') 116 else: 117 print('shopping') 118 119 a = 1 120 b = 0 121 122 """ 123 循环语句 124 while 125 """ 126 counter = 1 127 128 while counter <= 10: 129 counter += 1 130 print(counter) 131 else: 132 print("end") 133 """ 134 循环语句 135 for 136 主要是用来遍历/循环 序列或者集合、字典 137 for 自定义变量 in 数组列表: 138 print(打印出 自定义变量) 139 """ 140 fruits = ['banana','apple','mango'] 141 for fruit in fruits: 142 print('当前水果:',fruit) 143 """ 144 当前水果: banana 145 当前水果: apple 146 当前水果: mango 147 """ 148 149 a = [['apple','orange','banana','grape'],(1,2,3)] 150 for x in a: 151 for y in x: 152 print(y,end='') 153 else: 154 print('fruit is gone') # appleorangebananagrape123fruit is gone 155 # break终止循环 continue终止本次,循环继续 156 a = [1,2,3] 157 for x in a: 158 if x==2: 159 continue#break 160 print(x) 161 #range循环次数 range(开始,结束,间隔<步长>) 162 for x in range(10,0,-2): 163 print(x,end='|') 164 165 a = [1,2,3,4,5,6,7,8] 166 for i in range(0,len(a),2): 167 print(a[i],end='|') 168 169 b = a[0:len(a):2] 170 print(b) 171 172 def printme(str): 173 #打印任何传入的字符串 174 print(str) 175 return 176 printme("我要调用用户自定义函数!") 177 printme("我要再次调用同一函数!") 178 179 import time; 180 localtime = time.localtime(time.time()) 181 print("当前时间戳为:",localtime) 182 print(time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())) 183 184 import calendar 185 186 cal = calendar.month(2020,6) 187 print("以下输出2020年6月份的日历:") 188 print(cal) 189 190 191 """ 192 枚举 193 enum模块是系统内置模块,可以直接使用import导入,但是在导入的时候,不建议使用import enum将enum模块中的所有数据都导入,一般使用的最多的就是enum模块中的Enum、IntEnum、unique这几项 194 """ 195 196 # 导入枚举类 197 from enum import Enum 198 199 200 # 继承枚举类 201 class color(Enum): 202 YELLOW = 1 203 BEOWN = 1 204 # 注意BROWN的值和YELLOW的值相同,这是允许的,此时的BROWN相当于YELLOW的别名 205 RED = 2 206 GREEN = 3 207 PINK = 4 208 209 210 class color2(Enum): 211 YELLOW = 1 212 RED = 2 213 GREEN = 3 214 PINK = 4 215 216 217 print(color.YELLOW) # color.YELLOW 218 print(type(color.YELLOW)) # <enum 'color'> 219 220 print(color.YELLOW.value) # 1 221 print(type(color.YELLOW.value)) # <class 'int'> 222 223 print(color.YELLOW == 1) # False 224 print(color.YELLOW.value == 1) # True 225 print(color.YELLOW == color.YELLOW) # True 226 print(color.YELLOW == color2.YELLOW) # False 227 print(color.YELLOW is color2.YELLOW) # False 228 print(color.YELLOW is color.YELLOW) # True 229 230 print(color(1)) # color.YELLOW 231 print(type(color(1))) # <enum 'color'>