Python中for循环相关的几个小练习，生成指定位数的验证码序列，移位加密

  1 # 1.键盘录入的字符串（假设字符串中只包含小写字母和空格）进行加密操作，
  2 # 加密的规则是a变d，b变e，c变f，??，x变a，y变b，z变c，空格不变，返回加密后的字符串
  3 # 97 98 99 100   x = 120(97) y = 121(98) z = 122(99)
  4
  5 c_in = input("输入一个字母串：")
  6 mi_c = ‘‘
  7 for c in c_in:
  8     if 97 <= ord(c) < 120:
  9         mi_c += chr(ord(c)+3)
 10     elif 120 <= ord(c) <= 122:
 11         mi_c += chr(ord(c)-23)
 12     else:
 13         mi_c += ‘ ‘
 14 print("加密后：",mi_c)
 15
 16 # 2.键盘录入指定长度生成对应的验证码（由数字和大小写英文字母构成的随机字符串）。
 17 #方法一
 18 import random
 19 yzm = int(input(‘输入验证码位数：‘))
 20 zimu = random.randint(1,yzm)
 21 daxie = random.randint(1,zimu)
 22 xxie = zimu - daxie
 23 shuzi = yzm - zimu
 24 str_1 = random.sample(range(0,10),shuzi)    #生成数字
 25 str_2 = random.sample(range(97,123),xxie)   #生成小写字母
 26 str_3 = random.sample(range(65,91),daxie)  #生成大写字母
 27 str_4 = str_2 + str_3
 28 str_5 = []
 29 for inn in str_4:
 30     str_5.append(chr(inn))
 31 str_6 = str_1 + str_5
 32 for inn in str_6:
 33     print(inn,end=‘‘)
 34
 35 #方法二
 36 import random
 37 yzmlen = int(input(‘输入验证码位数：‘))
 38 sz = list(range(0, 10))
 39 zm = []
 40 zmb = list(range(97, 123)) + list(range(65, 91))
 41 for inn in zmb:
 42     zm.append(chr(inn))
 43 mlist = sz + zm
 44 yzm = random.sample(mlist, yzmlen)
 45 for inn in yzm:
 46     print(inn,end=‘‘)
 47
 48
 49
 50 # 3.自定义一个列表，最大的与第一个元素交换，最小的与最后一个元素交换，输出列表
 51 #
 52 lis = [12, 34, 56, 78, 99, 43, 1, 33, 75]
 53 max_i = 0
 54 min_i = -1
 55 for inn in range(1, len(lis)-1):
 56     if lis[max_i] < lis[inn]:
 57         lis[max_i], lis[inn] = lis[inn], lis[max_i]
 58     if lis[min_i] > lis[inn]:
 59         lis[min_i], lis[inn] = lis[inn], lis[min_i]
 60 print(lis)
 61
 62
 63 #4.自定义一个数字列表，求列表中第二大数的下标
 64
 65 list1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
 66 max_index = 0
 67 sec_index = 0
 68 for index in range(1,len(list1)-1):
 69     if list1[index] > list1[max_index]:
 70         max_index = index
 71 for index in range(1,len(list1)-1):
 72     if max_index != index:
 73         if list1[index] > list1[sec_index]:
 74             sec_index = index
 75     else:
 76         continue
 77 print("列表",list1,"\n其中第二大的元素%d 索引是 %d"%(list1[sec_index],sec_index))
 78 # #
 79 # 5.已知有字符串"I wish you prosperity and a better tomorrow I hope you can do better self-improvement efforts”
 80 #     a. 获取每个字符出现的次数
 81 #     b. 获取出现次数最少的字符
 82 #     c. 获取字符串中的每个字符 存放于列表中 但是列表中不允许有重复的字符, 并对列表进行降序排序
 83 #
 84 str1 = ‘I wish you prosperity and a better tomorrow I hope you can do better self-improvement efforts‘
 85 ch_dic = {}
 86 lis = []
 87 for ch in str1:
 88     if ch not in ch_dic:
 89         ch_dic[ch] = 1
 90     else:
 91         ch_dic[ch] += 1
 92     if ch not in lis:
 93         lis.append(ch)
 94 print(ch_dic,lis,sep="\n")
 95
 96 str_s = None
 97 min_ch = min(ch_dic.values())
 98 for k,v in ch_dic.items():
 99     if v == min_ch:
100         str_s = k
101 print("出现最少次数的字符是",str_s)
102
103 lis.sort(reverse=True)
104 print(lis)
105
106 # 6.提取字符串中的数字 进而求和
107 #     "i13love14you520" ----> 13 + 14 + 520 = 547
108
109 str = ‘i13love14you520‘
110 str += ‘end‘
111 n_sum = 0
112 str1 = ‘‘
113 lis = []
114 for i in str:
115     if 48 <= ord(i) <= 57:
116         str1 += i
117     else:
118         if str1 != ‘‘:
119             lis.append(str1)
120             str1 = ‘‘
121 print(lis)
122 for inn in lis:
123     n_sum += int(inn)
124 print(n_sum )

原文地址：https://www.cnblogs.com/wenmo/p/11272776.html