数据类型（Data Type）
1、Numbers
1 >>>7+3 #加法 2 10 3 >>>7-3 #减法 4 4 5 >>>7*3 #乘法 6 21 7 >>>7/3 #除法 8 2 9 >>>5**2 #乘方 10 25 11 >>>7%3 #求余数 12 1 13 >>>a=7.0/2 #float除以int，结果为float 14 >>>print a,type(a) 15 3.5 <type 'float'>
2、Strings
1 >>>word=’Python’ 2 >>>word[0] 3 ‘P’ 4 >>>word[5] 5 ‘n’ 6 >>>word[-1] 7 ‘n’ 8 >>>word[-2] 9 ‘o’ 10 >>>word[-6] 11 ‘P’ 12 13 >>>word[0:2] 14 ‘Py’ 15 >>>word[2:5] 16 ‘tho’ 17 >>>word[:2] 18 ‘Py’ 19 >>>word[-2:] 20 ‘on’ 21 >>>word[:2]+word[2:] 22 ‘Python’ 23 >>>len(word) 24 6
+---+---+---+---+---+---+
| P | y | t | h | o | n |
+---+---+---+---+---+---+
0 1 2 3 4 5 6
-6 -5 -4 -3 -2 -1
字符串“Python”的序号，从左到右按0-6排序，从右到左(-1)-(-6)排序
3、Lists
1 >>>squares =[1,4,9,16,25] 2 >>>squares 3 [1,4,9,16,25] 4 >>>squares[0] 5 1 6 >>>squares[-1] 7 25 8 >>>squares[-3:] 9 [9,16,25] 10 >>>squares[:] #返回一个squares的拷贝，即新的list 11 [1,4,9,16,25] 12 >>>squares+[36,49,64,81,100] 13 [1,4,9,16,25,36,49,64,81,100] 14 15 >>>cubes = [1,8,27,65,125] 16 >>>4**3 #4的立方为64 17 64 18 >>>cubes[3] = 64 19 >>>cubes 20 [1,8,27,64,125] 21 >>>cubes.append(216) 22 >>>cubes.append(7**3) 23 >>>cubes 24 [1,8,27,64,125,216,343] 25 26 >>>letters = [‘a’,’b’,’c’,’d’,’e’,’f’,’g’] 27 >>>letters 28 [‘a’,’b’,’c’,’d’,’e’,’f’,’g’] 29 >>>letters[2:5] = [‘C’,’D’,’E’] 30 >>>letters 31 [‘a’,’b’,’C’,’D’,’E’,’f’,’g’] 32 >>>letters[2:5]=[] 33 >>>letters 34 [‘a’,’b’,’f’,’g’] 35 >>>letters[:]=[] 36 >>>letters 37 [] 38 39 >>>letters = [‘a’,’b’,’c’,’d’] 40 >>>len(letters) 41 4 42 43 >>>a=[‘a’,’b’,’c’] 44 >>>n=[1,2,3] 45 >>>x=[a,n] 46 >>>x 47 [[‘a’,’b’,’c’],[1,2,3]] 48 >>>x[0] 49 [‘a’,’b’,’c’] 50 >>>x[0][1] 51 ‘b‘
4、总结
变量不需要声明，不需要删除，可以直接回收使用。
type(): 查询数据类型
String和List区别：String只能读取，不能用等号(=)赋值替换，List即可读取，也可以直接用等号(=)赋值替换
