python自学2018/03/22-文件操作
一、打开文件、读、写
1 """ 2 打开方式 3 a = append 追加 4 w = 写文件 5 r = 只读 6 r+ = 读+追加 # 打开老文件 7 w+ = 追加+读 # 创建新文件，用处不大 8 rb = 读二进制文件 9 wb = 写二进制文件 # f.write('hello binary\n'.encode() ) 10 rU或r+U = 在读取时可以将\r\n自动转换成\n 11 """ 12 13 # 打开文件，赋值给文件句柄 14 f = open('yesterday', 'w', encoding='utf-8') 15 with open('yesterday', 'r', encoding='utd-8') as f: # 自动关闭 16 f.read() 17 18 # 读文件 19 print(f.read(5)) # 读前50个字符 20 print(f.readline()) # 读一行 21 f.readable() # 判断文件是否可读 22 23 # 写文件 24 f.write('1,\n') 25 f.write('2') 26 f.writable() # 判断文件是否可写 27 28 # 返回文件句柄所在位置 29 print(f.tell()) 30 # 更改文件句柄所在位置 31 f.seek(0) 32 # 判断文件句柄是否可移动 33 f.seekable() 34 35 # 返回文件编码 36 print(f.encoding) 37 38 # 返回文件名 39 print(f.name) 40 41 # 将write的内容实时刷新到硬盘上 42 print(f.flush()) 43 print(f.buffer) 44 45 # 关闭文件 46 f.close() 47 f.clised() # 判断文件是否关闭 48 49 # 保留文件前10个字符，其余内容删除 50 f.truncate(10) # 文件打开方式应该使用'a'
二、修改文件内容并储存为新文件
1 f = open('yesterday', 'r', encoding='utf-8') 2 f_new = open('yesterday.new', 'w', encoding='utf-8') 3 4 for line in f: 5 if '有那么多肆意的快乐等我享受' in line: 6 line = line.replace('我', 'Alex', 1) 7 f_new.write(line) 8 9 f.close() 10 f_new.close()
附：yueterday文件内容
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Alex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Alex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
