Python3 文件读写注意事项（指针问题）

 C:\Users\Administrator\AppData\Local\Programs\Python\Python35\python.exe E:/python/day2/op.py
 Somehow, it seems the love I knew was always the most destructive kind
 不知为何，我经历的爱情总是最具毁灭性的的那种
 Yesterday when I was young
 昨日当我年少轻狂
 The taste of life was sweet
 生命的滋味是甜的
 As rain upon my tongue
 就如舌尖上的雨露
 I teased at life as if it were a foolish game
 我戏弄生命 视其为愚蠢的游戏
 The way the evening breeze
 就如夜晚的微风
 May tease the candle flame
 逗弄蜡烛的火苗
 The thousand dreams I dreamed
 我曾千万次梦见
 The splendid things I planned
 那些我计划的绚丽蓝图
 I always built to last on weak and shifting sand
 但我总是将之建筑在易逝的流沙上
 I lived by night and shunned the naked light of day
 我夜夜笙歌 逃避白昼赤裸的阳光
 And only now I see how the time ran away
 事到如今我才看清岁月是如何匆匆流逝
 Yesterday when I was young
 昨日当我年少轻狂
 So many lovely songs were waiting to be sung
 有那么多甜美的曲儿等我歌唱
 So many wild pleasures lay in store for me
 有那么多肆意的快乐等我享受
 And so much pain my eyes refused to see
 还有那么多痛苦 我的双眼却视而不见
 I ran so fast that time and youth at last ran out
 我飞快地奔走 最终时光与青春消逝殆尽
 I never stopped to think what life was all about
 我从未停下脚步去思考生命的意义
 And every conversation that I can now recall
 如今回想起的所有对话
 Concerned itself with me and nothing else at all
 除了和我相关的 什么都记不得了
 The game of love I played with arrogance and pride
 我用自负和傲慢玩着爱情的游戏
 And every flame I lit too quickly, quickly died
 所有我点燃的火焰都熄灭得太快
 The friends I made all somehow seemed to slip away
 所有我交的朋友似乎都不知不觉地离开了
 And only now I'm left alone to end the play, yeah
 只剩我一个人在台上来结束这场闹剧
 Oh, yesterday when I was young
 噢 昨日当我年少轻狂
 So many, many songs were waiting to be sung
 有那么那么多甜美的曲儿等我歌唱
 So many wild pleasures lay in store for me
 有那么多肆意的快乐等我享受
 And so much pain my eyes refused to see
 还有那么多痛苦 我的双眼却视而不见
 There are so many songs in me that won't be sung
 我有太多歌曲永远不会被唱起
 I feel the bitter taste of tears upon my tongue
 我尝到了舌尖泪水的苦涩滋味
 The time has come for me to pay for yesterday
 终于到了付出代价的时间 为了昨日
 When I was young
 当我年少轻狂 111111111111111!!!!!!! 

 f = open('yesterday') #文件句柄
 data = f.read()
 data2 = f.read()
 print(data,'111111111111111!!!!!!!',data2)

这里我们打印了print（data1，data2），但是为什么data2没有read出来？

很简单，python文件读取中遵循着一个指针，可以理解为我们打字光标，当你打字打了很多的时候，光标不停往后移动，理解为read不停读取字符串，但是当读取完的时候，光标不会自动移回去，所以我们要手动的移回去才能在读取一遍，不然光标后面就无字符串可读取，所以没有print出来。

 f.seek(0)#调整指针