通過for ... in ...:的語法結構，我們可以遍歷字符串、列表、元組、字典等數據結構。
注意python語法的縮進
字符串遍歷
>>> a_str = "hello itcast" >>> for char in a_str: ... print(char,end=' ') ... h e l l o i t c a s t 列表遍歷
>>> a_list = [1, 2, 3, 4, 5] >>> for num in a_list: ... print(num,end=' ') ... 1 2 3 4 5 元組遍歷
>>> a_turple = (1, 2, 3, 4, 5) >>> for num in a_turple: ... print(num,end=" ") 1 2 3 4 5 字典遍歷
<1> 遍歷字典的key（鍵）
<2> 遍歷字典的value（值）
<3> 遍歷字典的項（元素）
<4> 遍歷字典的key-value（鍵值對）
實現帶下標索引的遍歷
>>> chars = ['a', 'b', 'c', 'd'] >>> i = 0 >>> for chr in chars: ... print("%d %s"%(i, chr)) ... i += 1 ... 0 a 1 b 2 c 3 d enumerate()
>>> chars = ['a', 'b', 'c', 'd'] >>> for i, chr in enumerate(chars): ... print i, chr ... 0 a 1 b 2 c 3 d