一.控制流程之if判断
1、什么是if判断
判断一个条件如果成立则。。。不成立则。。。
2、为何要有if判断
让计算机能够像人一样具有判断能力
3、如何用if判断
1 ''' 2 # 语法1: 3 ''' 4 if 条件1: 5 code1 6 code2 7 code3 8 ...... 9 ''' 10 # age=18 11 # if age != 18: 12 # print('你好啊小伙子') 13 # print('加个微信吧...') 14 # print('other code...') 15 16 # 语法2: 17 ''' 18 if 条件: 19 code1 20 code2 21 code3 22 ...... 23 else: 24 code1 25 code2 26 code3 27 ...... 28 ''' 29 # age=18 30 # sex='male' 31 # wuzhong='human' 32 # is_beautiful=True 33 # 34 # if age > 16 and age < 22 and sex == 'female' and 35 # wuzhong == 'human' and is_beautiful: 36 # print('开始表白...') 37 # else: 38 # print('阿姨好,我逗你玩呢...') 39 40 41 # 语法3: 42 ''' 43 if 条件1: 44 if 条件2: 45 code1 46 code2 47 code3 48 code2 49 code3 50 ...... 51 ''' 52 # age = 18 53 # sex = 'female' 54 # wuzhong = 'human' 55 # is_beautiful = True 56 # is_successful = True 57 # 58 # if age > 16 and age < 22 and sex == 'female' and wuzhong == 'human' and is_beautiful: 59 # print('开始表白...') 60 # if is_successful: 61 # print('在一起') 62 # else: 63 # print('阿姨再见....') 64 # else: 65 # print('阿姨好,我逗你玩呢...') 66 67 # 语法4: 68 ''' 69 if 条件1: 70 子代码块1 71 elif 条件2: 72 子代码块2 73 elif 条件3: 74 子代码块3 75 elif 条件4: 76 子代码块4 77 ......... 78 else: 79 子代码块5 80 ''' 81 82 score = input('your score>>: ') 83 score=int(score) 84 if score >= 90: 85 print('优秀') 86 elif score >= 80: 87 print('良好') 88 elif score >= 70: 89 print('普通') 90 else: 91 print('很差')