今天学习的关于python的list和tuple

   1:  ‘‘‘
   2:  数组 有list和tuple之分
   3:  ‘‘‘
   4:   
   5:  classmates=[‘a‘,‘b‘,‘c‘,‘d‘]
   6:  print(classmates)
   7:  length=len(classmates)
   8:  print(length)#4
   9:  print(classmates[0]+classmates[1]) # ab
  10:  #print(classmates[5])#IndexError: list index out of range
  11:  print(classmates[-1])#!最后一个元素的索引是-1
  12:  classmates.append(88)#在最后加个元素88
  13:  print(classmates)
  14:  classmates.insert(2,45)
  15:  ‘‘‘
  16:      向第二个位置增加一个45
  17:  ‘‘‘
  18:  print(classmates)
  19:  classmates.pop(-2)
  20:  ‘‘‘
  21:      删除倒数第二个元素
  22:  ‘‘‘
  23:  print(classmates)
  24:  a=[[1,2,3],[4,5,6],[7,8,9]]
  25:  print(a)
  26:   
  27:   
  28:  ‘‘‘
  29:  tuple 不能变，一旦定义不能改。一个tuple 被定义后元素就必须定下来。
  30:  ‘‘‘
  31:  classmates=(‘a‘,‘b‘,‘c‘)
  32:  p=[‘asp‘,‘php‘]
  33:  s=[‘python‘,‘java‘,p,‘scheme‘]
  34:  print(s[2][1])
  35:  a=()
  36:  print(a)
  37:  #定义只有一个元素的tuple的时候必须在定义后面加一个“，”
  38:  a=(1,)
  39:  print(a)
  40:  ‘‘‘
  41:  输出为（1，）
  42:  ‘‘‘
  43:   
  44:  a=(1)
  45:  print(a)#输出为1
  46:  #但是这样可以变:
  47:  L=(‘a‘,‘b‘,[1,2])
  48:  print(L)
  49:  L[2].append(54)
  50:  print(L)
  51:  #但这样变的只是L中的tuple。
  52:  L = [
  53:      [‘Apple‘, ‘Google‘, ‘Microsoft‘],
  54:      [‘Java‘, ‘Python‘, ‘Ruby‘, ‘PHP‘],
  55:      [‘Adam‘, ‘Bart‘, ‘Lisa‘]
  56:  ]
  57:  print(L[0][0],L[1][1],L[2][2])
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