[TOC] 遍歷 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 ## 1. 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 ~~~ ## 2. 列表遍歷 ~~~ >>> a_list = [1, 2, 3, 4, 5] >>> for num in a_list: ... print(num,end=' ') ... 1 2 3 4 5 ~~~ ## 3. 元組遍歷 ~~~ >>> a_turple = (1, 2, 3, 4, 5) >>> for num in a_turple: ... print(num,end=" ") 1 2 3 4 5 ~~~ ## 4. 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） 遍歷 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） 想一想，如何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 ~~~ ## 5. enumerate() 帶下標 ~~~ >>> chars = ['a', 'b', 'c', 'd'] >>> for i, chr in enumerate(chars): ... print i, chr ... 0 a 1 b 2 c 3 d >>> 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 >>> chars = ['a', 'b', 'c', 'd'] >>> for i, chr in enumerate(chars): ... print i, chr ... 0 a 1 b 2 c 3 d ~~~