首先生成一个字典:

In [17]: dic={}

In [18]: dic.fromkeys('abcde',100)
Out[18]: {'a': 100, 'b': 100, 'c': 100, 'd': 100, 'e': 100}

利用for循环遍历字典的k值:

In [21]: for k in dict1:
   ....:     print(k)
   ....:     
a
c
b
e
d

利用for循环遍历字典的 k 值,并打印出 k 值和 values 值:

In [22]: for k in dict1:
    print(k),dict1[k]
   ....:     
a 100
c 100
b 100
e 100
d 100

进行格式化输出与 output 美化之后:

In [23]: for k in dict1:
    print("%s : %s" % (k,dict1[k]))
   ....:     
a : 100
c : 100
b : 100
e : 100
d : 100

我们也可以使用 items 将字典输出为列表:

In [24]: dict1.it
dict1.items       dict1.iteritems   dict1.iterkeys    dict1.itervalues  

In [24]: dict1.items()
Out[24]: [('a', 100), ('c', 100), ('b', 100), ('e', 100), ('d', 100)]

使用 for 循环遍历这个列表为:

In [25]: for i in dict1.items():print i
('a', 100)
('c', 100)
('b', 100)
('e', 100)
('d', 100)

也可以指定两个变量接收值:

In [27]: for i,v in dict1.items():print i,v
a 100
c 100
b 100
e 100
d 100

直接对字典进行访问,不加任何的方法的话,遍历出来的是字典的k值:

In [29]: for i in dict1:print i            
a
c
b
e
d

如果想要输出 values 呢,还是可以像前面一样进行取值:

In [30]: for i in dict1:print i,dict1[i]
a 100
c 100
b 100
e 100
d 100

小时候背过的乘法口诀,我们通过 Python 也可以写出来,代码如下:

#!usr/local/python3/bin/python

for i in range(1,10):      #指定有多少列
    for j in range(1,i+1):      #嵌套指定有多少行,
#        print("%s * %s = %s" % (j,i,j*i),end='   ')
        print("{0} * {1} = {2}".format(j,i,j*i),end='   ')        
                #格式化输出,当前循环结束之前以空格分割
    print("\n")     #循环结束重新进入下一个循环的时候进行换行

最后结果如下:

[root@izj6cdhdoq5a5z7lfkmaeaz ~]# python nine.py

1 * 1 = 1   

1 * 2 = 2   2 * 2 = 4   

1 * 3 = 3   2 * 3 = 6   3 * 3 = 9   

1 * 4 = 4   2 * 4 = 8   3 * 4 = 12   4 * 4 = 16   

1 * 5 = 5   2 * 5 = 10   3 * 5 = 15   4 * 5 = 20   5 * 5 = 25   

1 * 6 = 6   2 * 6 = 12   3 * 6 = 18   4 * 6 = 24   5 * 6 = 30   6 * 6 = 36   

1 * 7 = 7   2 * 7 = 14   3 * 7 = 21   4 * 7 = 28   5 * 7 = 35   6 * 7 = 42   7 * 7 = 49   

1 * 8 = 8   2 * 8 = 16   3 * 8 = 24   4 * 8 = 32   5 * 8 = 40   6 * 8 = 48   7 * 8 = 56   8 * 8 = 64   

1 * 9 = 9   2 * 9 = 18   3 * 9 = 27   4 * 9 = 36   5 * 9 = 45   6 * 9 = 54   7 * 9 = 63   8 * 9 = 72   9 * 9 = 81