Python字符串截取时总是有些糊涂，从官网上找到一个图示，理解Python字符串是如何标记，的具体含义图示如下：
+---+---+---+---+---+---+
| P | y | t | h | o | n |
+---+---+---+---+---+---+
0 1 2 3 4 5 6
-6 -5 -4 -3 -2 -1
>>> word[:2] # character from the beginning to position 2 (excluded) ‘Py‘ >>> word[4:] # characters from position 4 (included) to the end ‘on‘ >>> word[-2:] # characters from the second-last (included) to the end ‘on‘
原文：https://www.cnblogs.com/frisk/p/11568441.html