{"id":200,"date":"2023-10-26T16:34:22","date_gmt":"2023-10-26T08:34:22","guid":{"rendered":"http:\/\/ai.gitpp.com\/?p=200"},"modified":"2023-10-27T09:36:20","modified_gmt":"2023-10-27T01:36:20","slug":"7-%e8%be%93%e5%85%a5%e5%92%8c%e8%be%93%e5%87%ba","status":"publish","type":"post","link":"http:\/\/ai.gitpp.com\/index.php\/2023\/10\/26\/7-%e8%be%93%e5%85%a5%e5%92%8c%e8%be%93%e5%87%ba\/","title":{"rendered":"\u300aPython\u5165\u95e8\u6559\u7a0b\u300b7. \u8f93\u5165\u548c\u8f93\u51fa"},"content":{"rendered":"\n
    \n
  1. \u5f00\u80c3\u83dc<\/li>\n\n\n\n
  2. \u4f7f\u7528 Python \u89e3\u91ca\u5668<\/a><\/li>\n\n\n\n
  3. \u975e\u6b63\u5f0f\u4ecb\u7ecdPython<\/a><\/li>\n\n\n\n
  4. \u6df1\u5165\u6d41\u7a0b\u63a7\u5236<\/a><\/li>\n\n\n\n
  5. \u6570\u636e\u7ed3\u6784<\/a><\/li>\n\n\n\n
  6. \u6a21\u5757<\/a><\/li>\n\n\n\n
  7. \u8f93\u5165\u548c\u8f93\u51fa<\/a><\/li>\n\n\n\n
  8. \u9519\u8bef\u548c\u5f02\u5e38<\/a><\/li>\n\n\n\n
  9. \u7c7b<\/a><\/li>\n\n\n\n
  10. \u6807\u51c6\u5e93\u7684\u7b80\u660e\u4ecb\u7ecd<\/a><\/li>\n\n\n\n
  11. \u6807\u51c6\u5e93\u7684\u7b80\u660e\u4ecb\u7ecd\uff08\u7b2c\u4e8c\u90e8\u5206\uff09<\/a><\/li>\n\n\n\n
  12. \u73b0\u5728\u5e72\u4ec0\u4e48?<\/a><\/li>\n\n\n\n
  13. \u4ea4\u4e92\u5f0f\u8f93\u5165\u7f16\u8f91\u53ca\u5386\u53f2\u66ff\u4ee3<\/a><\/li>\n\n\n\n
  14. \u6d6e\u70b9\u7b97\u672f: \u95ee\u9898\u548c\u9650\u5236<\/a><\/li>\n<\/ol>\n\n\n\n

    \u6709\u591a\u79cd\u65b9\u5f0f\u53ef\u4ee5\u5c55\u73b0\u4e00\u4e2a\u7a0b\u5e8f\u7684\u8f93\u51fa; \u6570\u636e\u53ef\u4ee5\u4ee5\u4e00\u79cd\u53ef\u8bfb\u7684\u5f62\u5f0f\u8f93\u51fa, \u6216\u8005\u662f\u4fdd\u5b58\u4e8e\u4e00\u4e2a\u6587\u4ef6\u4fbf\u4e8e\u4ee5\u540e\u4f7f\u7528. \u672c\u7ae0\u5c31\u5c06\u8ba8\u8bba\u51e0\u79cd\u53ef\u80fd.<\/p>\n\n\n\n

    7.1. \u8f93\u51fa\u683c\u5f0f\u7f8e\u5316<\/a><\/h2>\n\n\n\n

    \u81f3\u4eca\u4e3a\u6b62, \u6211\u4eec\u77e5\u9053\u4e86\u4e24\u79cd\u8f93\u51fa\u503c\u7684\u65b9\u5f0f: \u8868\u8fbe\u5f0f\u8bed\u53e5<\/em> \u548c print()<\/code><\/a> \u51fd\u6570. (\u7b2c\u4e09\u79cd\u65b9\u5f0f\u662f\u4f7f\u7528\u6587\u4ef6\u5bf9\u8c61\u7684 write()<\/code> \u65b9\u6cd5; \u6807\u51c6\u8f93\u51fa\u6587\u4ef6\u53ef\u4ee5\u7528 sys.stdout<\/code> \u5f15\u7528. \u53c2\u8003\u5e93\u624b\u518c\u4e86\u89e3\u66f4\u591a\u7684\u4fe1\u606f.)<\/p>\n\n\n\n

    \u4e00\u822c\u6765\u8bf4\u4f60\u4f1a\u5e0c\u671b\u66f4\u591a\u7684\u63a7\u5236\u5176\u8f93\u51fa\u683c\u5f0f, \u800c\u4e0d\u662f\u7b80\u5355\u7684\u4ee5\u7a7a\u683c\u5206\u5272. \u6709\u4e24\u79cd\u65b9\u5f0f\u683c\u5f0f\u5316\u4f60\u7684\u8f93\u51fa; \u7b2c\u4e00\u79cd\u65b9\u5f0f\u662f\u7531\u4f60\u81ea\u5df1\u63a7\u5236; \u4f7f\u7528\u5b57\u7b26\u4e32\u5207\u7247\u548c\u8fde\u63a5\u64cd\u4f5c, \u6765\u5b9e\u73b0\u4f60\u6240\u60f3\u8c61\u7684\u5916\u89c2. \u6807\u51c6\u6a21\u5757 string<\/code><\/a> \u5305\u542b\u4e86\u4e00\u4e9b\u6709\u7528\u7684\u64cd\u4f5c, \u7528\u4ee5\u586b\u5145\u5b57\u7b26\u4e32\u81f3\u67d0\u4e00\u7ed9\u5b9a\u7684\u5bbd\u5ea6; \u5f88\u5feb\u5c31\u4f1a\u8ba8\u8bba\u8fd9\u4e9b. \u7b2c\u4e8c\u79cd\u65b9\u5f0f\u662f\u4f7f\u7528 str.format()<\/code><\/a> \u65b9\u6cd5.<\/p>\n\n\n\n

    string<\/code><\/a> \u6a21\u5757\u5305\u542b\u4e86\u4e00\u4e2a\u7c7b\u6a21\u677f, \u63d0\u4f9b\u4e86\u53e6\u4e00\u79cd\u66ff\u6362\u5b57\u7b26\u4e32\u7684\u65b9\u5f0f.<\/p>\n\n\n\n

    \u8fd8\u6709\u4e00\u4e2a\u95ee\u9898, \u5f53\u7136\u4e86: \u5982\u4f55\u628a\u503c\u8f6c\u6210\u5b57\u7b26\u4e32? \u5e78\u8fd0\u7684\u662f, Python \u6709\u591a\u79cd\u65b9\u5f0f\u5c06\u4efb\u4f55\u503c\u8f6c\u4e3a\u5b57\u7b26\u4e32: \u5c06\u5b83\u4f20\u7ed9 repr()<\/code><\/a> \u6216 str()<\/code><\/a> \u51fd\u6570.<\/p>\n\n\n\n

    str()<\/code><\/a> \u51fd\u6570\u610f\u5473\u7740\u8fd4\u56de\u4e00\u4e2a\u7528\u6237\u6613\u8bfb\u7684\u8868\u8fbe\u5f62\u5f0f, \u800c repr()<\/code><\/a> \u5219\u610f\u5473\u7740\u4ea7\u751f\u4e00\u4e2a\u89e3\u91ca\u5668\u6613\u8bfb\u7684\u8868\u8fbe\u5f62\u5f0f (\u6216\u8005\u5982\u679c\u6ca1\u6709\u8fd9\u6837\u7684\u8bed\u6cd5\u4f1a\u7ed9\u51fa SyntaxError<\/code><\/a> ). \u5bf9\u4e8e\u90a3\u4e9b\u6ca1\u6709\u7279\u6b8a\u8868\u8fbe\u7684\u5bf9\u8c61, str()<\/code><\/a> \u5c06\u4f1a\u4e0e repr()<\/code><\/a> \u8fd4\u56de\u76f8\u540c\u7684\u503c. \u5f88\u591a\u7684\u503c, \u5982\u6570\u5b57\u6216\u4e00\u4e9b\u5982\u5217\u8868\u548c\u5b57\u5178\u90a3\u6837\u7684\u7ed3\u6784, \u4f7f\u7528\u8fd9\u4e24\u4e2a\u51fd\u6570\u7684\u7ed3\u679c\u5b8c\u5168\u4e00\u81f4. \u5b57\u7b26\u4e32\u4e0e\u6d6e\u70b9\u578b\u5219\u6709\u4e24\u79cd\u4e0d\u540c\u7684\u8868\u8fbe.<\/p>\n\n\n\n

    \u4f8b\u5982:>>> <\/strong>s = ‘Hello, world.’ >>> <\/strong>str(s) ‘Hello, world.’ >>> <\/strong>repr(s) “‘Hello, world.'” >>> <\/strong>str(1.0\/7.0) ‘0.142857142857’ >>> <\/strong>repr(1.0\/7.0) ‘0.14285714285714285’ >>> <\/strong>x = 10 * 3.25 >>> <\/strong>y = 200 * 200 >>> <\/strong>s = ‘The value of x is ‘ + repr(x) + ‘, and y is ‘ + repr(y) + ‘…’ >>> <\/strong>print(s) The value of x is 32.5, and y is 40000… >>> <\/strong># The repr() of a string adds string quotes and backslashes:<\/em>… <\/strong>hello = ‘hello, world\\n<\/strong>‘ >>> <\/strong>hellos = repr(hello) >>> <\/strong>print(hellos) ‘hello, world\\n’ >>> <\/strong># The argument to repr() may be any Python object:<\/em>… <\/strong>repr((x, y, (‘spam’, ‘eggs’))) “(32.5, 40000, (‘spam’, ‘eggs’))”<\/p>\n\n\n\n

    \u8fd9\u91cc\u6709\u4e24\u79cd\u65b9\u5f0f\u8f93\u51fa\u4e00\u4e2a\u5e73\u65b9\u4e0e\u7acb\u65b9\u7684\u8868:>>> <\/strong>for<\/strong> x in<\/strong> range(1, 11): …<\/strong> print(repr(x).rjust(2), repr(x*x).rjust(3), end=’ ‘) … <\/strong># Note use of ‘end’ on previous line \u6ce8\u610f\u524d\u4e00\u884c ‘end’ \u7684\u4f7f\u7528<\/em>…<\/strong> print(repr(x*x*x).rjust(4)) …<\/strong> 1 1 1 2 4 8 3 9 27 4 16 64 5 25 125 6 36 216 7 49 343 8 64 512 9 81 729 10 100 1000 >>> <\/strong>for<\/strong> x in<\/strong> range(1, 11): …<\/strong> print(‘{0:2d}<\/em>{1:3d}<\/em>{2:4d}<\/em>‘.format(x, x*x, x*x*x)) …<\/strong> 1 1 1 2 4 8 3 9 27 4 16 64 5 25 125 6 36 216 7 49 343 8 64 512 9 81 729 10 100 1000<\/p>\n\n\n\n

    (\u6ce8\u610f\u5728\u7b2c\u4e00\u4e2a\u4f8b\u5b50\u4e2d, \u6bcf\u5217\u95f4\u7684\u7a7a\u683c\u662f\u7531 print()<\/code><\/a> \u6dfb\u52a0\u7684: \u5b83\u603b\u4f1a\u5728\u6bcf\u4e2a\u53c2\u6570\u540e\u9762\u52a0\u4e2a\u7a7a\u683c.)<\/p>\n\n\n\n

    \u8fd9\u4e2a\u4f8b\u5b50\u5c55\u793a\u4e86\u5b57\u7b26\u4e32\u5bf9\u8c61\u7684 rjust()<\/code> \u65b9\u6cd5, \u5b83\u53ef\u4ee5\u5c06\u5b57\u7b26\u4e32\u9760\u53f3, \u5e76\u5728\u5de6\u8fb9\u586b\u5145\u7a7a\u683c. \u8fd8\u6709\u7c7b\u4f3c\u7684\u65b9\u6cd5, \u5982 ljust()<\/code> \u548c center()<\/code>. \u8fd9\u4e9b\u65b9\u6cd5\u5e76\u4e0d\u4f1a\u5199\u4efb\u4f55\u4e1c\u897f, \u5b83\u4eec\u4ec5\u4ec5\u8fd4\u56de\u65b0\u7684\u5b57\u7b26\u4e32. \u5982\u679c\u8f93\u5165\u5f88\u957f, \u5b83\u4eec\u5e76\u4e0d\u4f1a\u5bf9\u5b57\u7b26\u4e32\u8fdb\u884c\u622a\u65ad, \u4ec5\u4ec5\u8fd4\u56de\u6ca1\u6709\u4efb\u4f55\u53d8\u5316\u7684\u5b57\u7b26\u4e32; \u8fd9\u867d\u7136\u4f1a\u5f71\u54cd\u4f60\u7684\u5e03\u5c40, \u4f46\u662f\u8fd9\u4e00\u822c\u6bd4\u622a\u65ad\u7684\u8981\u597d. (\u5982\u679c\u4f60\u7684\u786e\u9700\u8981\u622a\u65ad, \u90a3\u4e48\u5c31\u589e\u52a0\u4e00\u4e2a\u5207\u7247\u7684\u64cd\u4f5c, \u5982 x.ljust(n)[:n]<\/code>.)<\/p>\n\n\n\n

    \u6709\u53e6\u4e00\u4e2a\u65b9\u6cd5, zfill()<\/code>, \u5b83\u4f1a\u5728\u6570\u5b57\u7684\u5de6\u8fb9\u586b\u5145 0. \u5b83\u77e5\u9053\u6b63\u8d1f\u53f7:>>> <\/strong>’12’.zfill(5) ‘00012’ >>> <\/strong>‘-3.14’.zfill(7) ‘-003.14’ >>> <\/strong>‘3.14159265359’.zfill(5) ‘3.14159265359’<\/p>\n\n\n\n

    str.format()<\/code><\/a> \u7684\u57fa\u672c\u4f7f\u7528\u5982\u4e0b:>>> <\/strong>print(‘We are the {}<\/em> who say “{}<\/em>!”‘.format(‘knights’, ‘Ni’)) We are the knights who say “Ni!”<\/p>\n\n\n\n

    \u62ec\u53f7\u53ca\u5176\u91cc\u9762\u7684\u5b57\u7b26 (\u79f0\u4f5c format field) \u5c06\u4f1a\u88ab format()<\/code><\/a> \u4e2d\u7684\u53c2\u6570\u66ff\u6362. \u5728\u62ec\u53f7\u4e2d\u7684\u6570\u5b57\u7528\u4e8e\u6307\u5411\u4f20\u5165\u5bf9\u8c61\u5728 format()<\/code><\/a> \u4e2d\u7684\u4f4d\u7f6e.>>> <\/strong>print(‘{0}<\/em> and {1}<\/em>‘.format(‘spam’, ‘eggs’)) spam and eggs >>> <\/strong>print(‘{1}<\/em> and {0}<\/em>‘.format(‘spam’, ‘eggs’)) eggs and spam<\/p>\n\n\n\n

    \u5982\u679c\u5728 format()<\/code><\/a> \u4e2d\u4f7f\u7528\u4e86\u5173\u952e\u5b57\u53c2\u6570, \u90a3\u4e48\u5b83\u4eec\u7684\u503c\u4f1a\u6307\u5411\u4f7f\u7528\u8be5\u540d\u5b57\u7684\u53c2\u6570.>>> <\/strong>print(‘This {food}<\/em> is {adjective}<\/em>.’.format( …<\/strong> food=’spam’, adjective=’absolutely horrible’)) This spam is absolutely horrible.<\/p>\n\n\n\n

    \u4f4d\u7f6e\u53ca\u5173\u952e\u5b57\u53c2\u6570\u53ef\u4ee5\u4efb\u610f\u7684\u7ed3\u5408:>>> <\/strong>print(‘The story of {0}<\/em>, {1}<\/em>, and {other}<\/em>.’.format(‘Bill’, ‘Manfred’, other=’Georg’)) The story of Bill, Manfred, and Georg.<\/p>\n\n\n\n

    '!a'<\/code> (\u4f7f\u7528 ascii()<\/code><\/a>), '!s'<\/code> (\u4f7f\u7528 str()<\/code><\/a>) \u548c '!r'<\/code> (\u4f7f\u7528 repr()<\/code><\/a>) \u53ef\u4ee5\u7528\u4e8e\u5728\u683c\u5f0f\u5316\u67d0\u4e2a\u503c\u4e4b\u524d\u5bf9\u5176\u8fdb\u884c\u8f6c\u5316:>>> <\/strong>import<\/strong>math<\/strong>>>> <\/strong>print(‘The value of PI is approximately {}<\/em>.’.format(math.pi)) The value of PI is approximately 3.14159265359. >>> <\/strong>print(‘The value of PI is approximately {!r}<\/em>.’.format(math.pi)) The value of PI is approximately 3.141592653589793.<\/p>\n\n\n\n

    \u53ef\u9009\u9879 ':'<\/code> \u548c\u683c\u5f0f\u6807\u8bc6\u7b26\u53ef\u4ee5\u8ddf\u7740 field name. \u8fd9\u5c31\u5141\u8bb8\u5bf9\u503c\u8fdb\u884c\u66f4\u597d\u7684\u683c\u5f0f\u5316. \u4e0b\u9762\u7684\u4f8b\u5b50\u5c06 Pi \u4fdd\u7559\u5230\u5c0f\u6570\u70b9\u540e\u4e09\u4f4d.>>> <\/strong>import<\/strong>math<\/strong>>>> <\/strong>print(‘The value of PI is approximately {0:.3f}<\/em>.’.format(math.pi)) The value of PI is approximately 3.142.<\/p>\n\n\n\n

    \u5728 ':'<\/code> \u540e\u4f20\u5165\u4e00\u4e2a\u6574\u6570, \u53ef\u4ee5\u4fdd\u8bc1\u8be5\u57df\u81f3\u5c11\u6709\u8fd9\u4e48\u591a\u7684\u5bbd\u5ea6. \u7528\u4e8e\u7f8e\u5316\u8868\u683c\u65f6\u5f88\u6709\u7528.>>> <\/strong>table = {‘Sjoerd’: 4127, ‘Jack’: 4098, ‘Dcab’: 7678} >>> <\/strong>for<\/strong> name, phone in<\/strong> table.items(): …<\/strong> print(‘{0:10}<\/em> ==> {1:10d}<\/em>‘.format(name, phone)) …<\/strong> Jack ==> 4098 Dcab ==> 7678 Sjoerd ==> 4127<\/p>\n\n\n\n

    \u5982\u679c\u4f60\u6709\u4e00\u4e2a\u7684\u786e\u5f88\u957f\u7684\u683c\u5f0f\u5316\u5b57\u7b26\u4e32, \u800c\u4f60\u4e0d\u60f3\u5c06\u5b83\u4eec\u5206\u5f00, \u90a3\u4e48\u5728\u683c\u5f0f\u5316\u65f6\u901a\u8fc7\u53d8\u91cf\u540d\u800c\u975e\u4f4d\u7f6e\u4f1a\u662f\u5f88\u597d\u7684\u4e8b\u60c5. \u6700\u7b80\u5355\u7684\u5c31\u662f\u4f20\u5165\u4e00\u4e2a\u5b57\u5178, \u7136\u540e\u4f7f\u7528\u65b9\u62ec\u53f7 '[]'<\/code> \u6765\u8bbf\u95ee\u952e\u503c :>>> <\/strong>table = {‘Sjoerd’: 4127, ‘Jack’: 4098, ‘Dcab’: 8637678} >>> <\/strong>print(‘Jack: {0[Jack]:d}<\/em>; Sjoerd: {0[Sjoerd]:d}<\/em>; ‘ ‘Dcab: {0[Dcab]:d}’.format(table)) Jack: 4098; Sjoerd: 4127; Dcab: 8637678<\/p>\n\n\n\n

    \u8fd9\u4e5f\u53ef\u4ee5\u901a\u8fc7\u5728 table \u53d8\u91cf\u524d\u4f7f\u7528 \u2018**\u2019 \u6765\u5b9e\u73b0\u76f8\u540c\u7684\u529f\u80fd.>>> <\/strong>table = {‘Sjoerd’: 4127, ‘Jack’: 4098, ‘Dcab’: 8637678} >>> <\/strong>print(‘Jack: {Jack:d}<\/em>; Sjoerd: {Sjoerd:d}<\/em>; Dcab: {Dcab:d}<\/em>‘.format(**table)) Jack: 4098; Sjoerd: 4127; Dcab: 8637678<\/p>\n\n\n\n

    \u5728\u7ed3\u5408\u65b0\u7684\u5185\u7f6e\u51fd\u6570 vars()<\/code><\/a> (\u8fd9\u4f1a\u4ee5\u5b57\u5178\u7684\u5f62\u5f0f\u8fd4\u56de\u6240\u6709\u7684\u5c40\u90e8\u53d8\u91cf) \u548c\u8fd9\u4e2a\u65f6\u4f1a\u7279\u522b\u6709\u7528.<\/p>\n\n\n\n

    \u8981\u4e86\u89e3\u66f4\u591a\u5173\u4e8e str.format()<\/code><\/a> \u7684\u77e5\u8bc6, \u53c2\u8003 Format String Syntax<\/a>.<\/p>\n\n\n\n

    7.1.1. \u65e7\u5f0f\u5b57\u7b26\u4e32\u683c\u5f0f\u5316<\/a><\/h3>\n\n\n\n

    %<\/code> \u64cd\u4f5c\u7b26\u4e5f\u53ef\u4ee5\u5b9e\u73b0\u5b57\u7b26\u4e32\u683c\u5f0f\u5316. \u5b83\u5c06\u5de6\u8fb9\u7684\u53c2\u6570\u4f5c\u4e3a\u7c7b\u4f3c sprintf()<\/code> \u5f0f\u7684\u683c\u5f0f\u5316\u5b57\u7b26\u4e32, \u800c\u5c06\u53f3\u8fb9\u7684\u4ee3\u5165, \u7136\u540e\u8fd4\u56de\u683c\u5f0f\u5316\u540e\u7684\u5b57\u7b26\u4e32. \u4f8b\u5982:>>> <\/strong>import<\/strong>math<\/strong>>>> <\/strong>print(‘The value of PI is approximately %5.3f<\/em>.’ % math.pi) The value of PI is approximately 3.142.<\/p>\n\n\n\n

    \u56e0\u4e3a str.format()<\/code><\/a> \u5f88\u65b0, \u5927\u591a\u6570\u7684 Python \u4ee3\u7801\u4ecd\u7136\u4f7f\u7528 %<\/code> \u64cd\u4f5c\u7b26. \u4f46\u662f\u56e0\u4e3a\u8fd9\u79cd\u65e7\u5f0f\u7684\u683c\u5f0f\u5316\u6700\u7ec8\u4f1a\u4ece\u8be5\u8bed\u8a00\u4e2d\u79fb\u9664, \u5e94\u8be5\u66f4\u591a\u7684\u4f7f\u7528 str.format()<\/code><\/a>.<\/p>\n\n\n\n

    \u66f4\u591a\u7684\u4fe1\u606f\u53ef\u4ee5\u5728 Old String Formatting Operations<\/a> \u4e2d\u627e\u5230.<\/p>\n\n\n\n

    7.2. \u8bfb\u548c\u5199\u6587\u4ef6<\/a><\/h2>\n\n\n\n

    open()<\/code><\/a> \u5c06\u4f1a\u8fd4\u56de\u4e00\u4e2a file object<\/a>, \u5e76\u4e14\u4e00\u822c\u4f7f\u7528\u4e24\u4e2a\u53c2\u6570\u8fdb\u884c\u4f7f\u7528: open(filename, mode)<\/code>.>>> <\/strong>f = open(‘\/tmp\/workfile’, ‘w’)<\/p>\n\n\n\n

    \u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u5305\u542b\u6587\u4ef6\u540d\u7684\u5b57\u7b26\u4e32. \u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u53e6\u4e00\u4e2a\u5b57\u7b26\u4e32, \u5305\u542b\u63cf\u8ff0\u6587\u4ef6\u5982\u4f55\u4f7f\u7528\u7684\u5b57\u7b26. mode<\/em> \u53ef\u4ee5\u662f 'r'<\/code> \u5982\u679c\u6587\u4ef6\u53ea\u8bfb, 'w'<\/code> \u53ea\u7528\u4e8e\u5199 (\u5982\u679c\u5b58\u5728\u540c\u540d\u6587\u4ef6\u5219\u5c06\u88ab\u5220\u9664), \u548c 'a'<\/code> \u7528\u4e8e\u8ffd\u52a0\u6587\u4ef6\u5185\u5bb9; \u6240\u5199\u7684\u4efb\u4f55\u6570\u636e\u90fd\u4f1a\u88ab\u81ea\u52a8\u589e\u52a0\u5230\u672b\u5c3e. 'r+'<\/code> \u540c\u65f6\u7528\u4e8e\u8bfb\u5199. mode<\/em> \u53c2\u6570\u662f\u53ef\u9009\u7684; 'r'<\/code> \u5c06\u662f\u9ed8\u8ba4\u503c.<\/p>\n\n\n\n

    \u4e00\u822c\u800c\u8a00, \u6587\u4ef6\u4ee5 text mode<\/em> \u6253\u5f00, \u8fd9\u5c31\u610f\u5473\u7740, \u4ece\u6587\u4ef6\u4e2d\u8bfb\u5199\u7684\u5b57\u7b26\u4e32, \u662f\u4ee5\u4e00\u79cd\u7279\u5b9a\u7684\u7f16\u7801\u8fdb\u884c\u7f16\u7801 (\u9ed8\u8ba4\u7684\u662f UTF-8). \u8ffd\u52a0\u5230 mode<\/em> \u540e\u7684 'b'<\/code> , \u5c06\u610f\u5473\u7740\u4ee5 binary mode<\/em> \u6253\u5f00\u6587\u4ef6: \u73b0\u5728\u7684\u6570\u636e\u662f\u4ee5\u5b57\u8282\u5bf9\u8c61\u7684\u5f62\u5f0f\u8fdb\u884c\u8bfb\u5199. \u8fd9\u4e2a\u6a21\u5f0f\u5e94\u8be5\u7528\u4e8e\u90a3\u4e9b\u4e0d\u5305\u542b\u6587\u672c\u7684\u6587\u4ef6.<\/p>\n\n\n\n

    \u5728\u6587\u672c\u6a21\u5f0f\u4e0b (text mode), \u9ed8\u8ba4\u662f\u5c06\u7279\u5b9a\u5e73\u53f0\u7684\u884c\u672b\u6807\u8bc6\u7b26 ( Unix \u4e0b\u4e3a \\n<\/code>, Windows \u4e0b\u4e3a \\r\\n<\/code> ) \u5728\u8bfb\u65f6\u8f6c\u4e3a \\n<\/code> \u800c\u5199\u65f6\u5c06 \\n<\/code> \u8f6c\u4e3a\u7279\u5b9a\u5e73\u53f0\u7684\u6807\u8bc6\u7b26. \u8fd9\u79cd\u9690\u85cf\u7684\u884c\u4e3a\u5bf9\u4e8e\u6587\u672c\u6587\u4ef6\u662f\u6ca1\u6709\u95ee\u9898\u7684, \u4f46\u662f\u5bf9\u4e8e\u4e8c\u8fdb\u5236\u6570\u636e\u50cf JPEG<\/code> \u6216 EXE<\/code> \u662f\u4f1a\u51fa\u95ee\u9898\u7684. \u5728\u4f7f\u7528\u8fd9\u4e9b\u6587\u4ef6\u65f6\u8bf7\u5c0f\u5fc3\u4f7f\u7528\u4e8c\u8fdb\u5236\u6a21\u5f0f.<\/p>\n\n\n\n

    7.2.1. \u6587\u4ef6\u5bf9\u8c61\u7684\u65b9\u6cd5<\/a><\/h3>\n\n\n\n

    \u672c\u8282\u4e2d\u5269\u4e0b\u7684\u4f8b\u5b50\u5047\u8bbe\u5df2\u7ecf\u521b\u5efa\u4e86\u4e00\u4e2a\u79f0\u4e3a f<\/code> \u7684\u6587\u4ef6\u5bf9\u8c61.<\/p>\n\n\n\n

    \u4e3a\u4e86\u8bfb\u53d6\u4e00\u4e2a\u6587\u4ef6\u7684\u5185\u5bb9, \u8c03\u7528 f.read(size)<\/code>, \u8fd9\u5c06\u8bfb\u53d6\u4e00\u5b9a\u6570\u76ee\u7684\u6570\u636e, \u7136\u540e\u4f5c\u4e3a\u5b57\u7b26\u4e32\u6216\u5b57\u8282\u5bf9\u8c61\u8fd4\u56de. size<\/em> \u662f\u4e00\u4e2a\u53ef\u9009\u7684\u6570\u5b57\u7c7b\u578b\u7684\u53c2\u6570. \u5f53 size<\/em> \u88ab\u5ffd\u7565\u4e86\u6216\u8005\u4e3a\u8d1f, \u90a3\u4e48\u8be5\u6587\u4ef6\u7684\u6240\u6709\u5185\u5bb9\u90fd\u5c06\u88ab\u8bfb\u53d6\u5e76\u4e14\u8fd4\u56de; \u5982\u679c\u6587\u4ef6\u6bd4\u4f60\u7684\u5185\u5b58\u5927\u4e24\u500d, \u90a3\u4e48\u5c31\u4f1a\u6210\u4e3a\u4f60\u7684\u95ee\u9898\u4e86. \u5426\u5219, \u6700\u591a size<\/em> \u5b57\u8282\u5c06\u88ab\u8bfb\u53d6\u5e76\u8fd4\u56de. \u5982\u679c\u5230\u8fbe\u4e86\u6587\u4ef6\u7684\u672b\u5c3e, f.read()<\/code> \u5c06\u4f1a\u8fd4\u56de\u4e00\u4e2a\u7a7a\u5b57\u7b26\u4e32 (''<\/code>).>>> <\/strong>f.read() ‘This is the entire file.\\n’ >>> <\/strong>f.read() ”<\/p>\n\n\n\n

    f.readline()<\/code> \u4f1a\u4ece\u6587\u4ef6\u4e2d\u8bfb\u53d6\u5355\u72ec\u7684\u4e00\u884c; \u5728\u6bcf\u4e2a\u5b57\u7b26\u4e32\u7684\u672b\u5c3e\u90fd\u4f1a\u7559\u4e0b\u6362\u884c\u7b26 (\\n<\/code>), \u9664\u975e\u662f\u8be5\u6587\u4ef6\u7684\u6700\u540e\u4e00\u884c\u5e76\u4e14\u6ca1\u6709\u4ee5\u6362\u884c\u7b26\u7ed3\u675f, \u8fd9\u4e2a\u5b57\u7b26\u624d\u4f1a\u88ab\u5ffd\u7565. \u8fd9\u5c31\u4f7f\u7ed3\u679c\u5f88\u660e\u786e; f.readline()<\/code> \u5982\u679c\u8fd4\u56de\u4e00\u4e2a\u7a7a\u5b57\u7b26\u4e32, \u90a3\u4e48\u6587\u4ef6\u5df2\u5230\u5e95\u4e86, \u800c\u5982\u679c\u662f\u4ee5 '\\n'<\/code> \u8868\u793a, \u90a3\u4e48\u5c31\u662f\u53ea\u5305\u884c\u4e00\u4e2a\u65b0\u884c.>>> <\/strong>f.readline() ‘This is the first line of the file.\\n’ >>> <\/strong>f.readline() ‘Second line of the file\\n’ >>> <\/strong>f.readline() ”<\/p>\n\n\n\n

    f.readlines()<\/code> \u5c06\u8fd4\u56de\u8be5\u6587\u4ef6\u4e2d\u5305\u542b\u7684\u6240\u6709\u884c. \u5982\u679c\u7ed9\u5b9a\u4e00\u4e2a\u53ef\u9009\u53c2\u6570 sizehint<\/em>, \u5b83\u5c31\u8bfb\u53d6\u8fd9\u4e48\u591a\u5b57\u8282, \u5e76\u4e14\u5c06\u8fd9\u4e9b\u5b57\u8282\u6309\u884c\u5206\u5272. \u8fd9\u7ecf\u5e38\u7528\u4e8e\u5141\u8bb8\u6309\u884c\u8bfb\u53d6\u4e00\u4e2a\u5927\u6587\u4ef6, \u4f46\u662f\u4e0d\u9700\u8981\u8f7d\u5165\u5168\u90e8\u7684\u6587\u4ef6\u65f6\u975e\u5e38\u6709\u7528. \u53ea\u4f1a\u8fd4\u56de\u5b8c\u6574\u7684\u884c.>>> <\/strong>f.readlines() [‘This is the first line of the file.\\n’, ‘Second line of the file\\n’]<\/p>\n\n\n\n

    \u53e6\u4e00\u79cd\u65b9\u5f0f\u662f\u8fed\u4ee3\u4e00\u4e2a\u6587\u4ef6\u5bf9\u8c61\u7136\u540e\u8bfb\u53d6\u6bcf\u884c. \u8fd9\u662f\u5185\u5b58\u6709\u6548, \u5feb\u901f, \u5e76\u7528\u6700\u5c11\u7684\u4ee3\u7801:>>> <\/strong>for<\/strong> line in<\/strong> f: …<\/strong> print(line, end=”) …<\/strong> This is the first line of the file. Second line of the file<\/p>\n\n\n\n

    \u8fd9\u4e2a\u65b9\u6cd5\u5f88\u7b80\u5355, \u4f46\u662f\u5e76\u6ca1\u6709\u63d0\u4f9b\u4e00\u4e2a\u5f88\u597d\u7684\u63a7\u5236. \u56e0\u4e3a\u4e24\u8005\u7684\u5904\u7406\u673a\u5236\u4e0d\u540c, \u6700\u597d\u4e0d\u8981\u6df7\u7528.<\/p>\n\n\n\n

    f.write(string)<\/code> \u5c06 string<\/em> \u5199\u5165\u5230\u6587\u4ef6\u4e2d, \u7136\u540e\u8fd4\u56de\u5199\u5165\u7684\u5b57\u7b26\u6570.>>> <\/strong>f.write(‘This is a test\\n<\/strong>‘) 15<\/p>\n\n\n\n

    \u5982\u679c\u8981\u5199\u5165\u4e00\u4e9b\u4e0d\u662f\u5b57\u7b26\u4e32\u7684\u4e1c\u897f, \u90a3\u4e48\u5c06\u9700\u8981\u5148\u8fdb\u884c\u8f6c\u6362:>>> <\/strong>value = (‘the answer’, 42) >>> <\/strong>s = str(value) >>> <\/strong>f.write(s) 18<\/p>\n\n\n\n

    f.tell()<\/code> \u8fd4\u56de\u6587\u4ef6\u5bf9\u8c61\u5f53\u524d\u6240\u5904\u7684\u4f4d\u7f6e, \u5b83\u662f\u4ece\u6587\u4ef6\u5f00\u5934\u5f00\u59cb\u7b97\u8d77\u7684\u5b57\u8282\u6570. \u8981\u6539\u53d8\u6587\u4ef6\u5f53\u524d\u7684\u4f4d\u7f6e, \u4f7f\u7528 f.seek(offset, from_what)<\/code>. \u8fd9\u4e2a\u4f4d\u7f6e\u662f\u901a\u8fc7\u5c06\u5f53\u524d\u4f4d\u7f6e\u52a0\u4e0a offset<\/em> \u6240\u5f97. from_what<\/em> \u7684\u503c, \u5982\u679c\u662f 0 \u8868\u793a\u5f00\u5934, \u5982\u679c\u662f 1 \u8868\u793a\u5f53\u524d\u4f4d\u7f6e, 2 \u8868\u793a\u6587\u4ef6\u7684\u7ed3\u5c3e. from_what<\/em> \u7684\u9ed8\u8ba4\u4e3a 0, \u5373\u4ece\u5f00\u5934\u5f00\u59cb.>>> <\/strong>f = open(‘\/tmp\/workfile’, ‘rb+’) >>> <\/strong>f.write(b’0123456789abcdef’) 16 >>> <\/strong>f.seek(5) # Go to the 6th byte in the file<\/em> 5 >>> <\/strong>f.read(1) b’5′ >>> <\/strong>f.seek(-3, 2) # Go to the 3rd byte before the end<\/em> 13 >>> <\/strong>f.read(1) b’d’<\/p>\n\n\n\n

    \u5728\u6587\u672c\u6587\u4ef6\u4e2d (\u90a3\u4e9b\u6253\u5f00\u6587\u4ef6\u7684\u6a21\u5f0f\u4e0b\u6ca1\u6709 b<\/code> \u7684), \u53ea\u4f1a\u76f8\u5bf9\u4e8e\u6587\u4ef6\u8d77\u59cb\u4f4d\u7f6e\u8fdb\u884c\u5b9a\u4f4d, (\u5982\u679c\u8981\u5b9a\u6587\u4ef6\u7684\u6700\u540e\u9762, \u8981\u7528 seek(0, 2)<\/code> ).<\/p>\n\n\n\n

    \u5f53\u4f60\u5904\u7406\u5b8c\u4e00\u4e2a\u6587\u4ef6\u540e, \u8c03\u7528 f.close()<\/code> \u4f1a\u5173\u95ed\u5b83, \u5e76\u91ca\u653e\u7cfb\u7edf\u7684\u8d44\u6e90. \u5728\u8c03\u7528\u5b8c f.close()<\/code> \u4e4b\u540e, \u5c1d\u8bd5\u4f7f\u7528\u90a3\u4e2a\u6587\u4ef6\u5bf9\u8c61\u662f\u4f1a\u5931\u8d25\u7684.>>> <\/strong>f.close() >>> <\/strong>f.read() Traceback (most recent call last): File “<stdin>”, line 1, in ? ValueError: I\/O operation on closed file<\/p>\n\n\n\n

    \u5f53\u5904\u7406\u4e00\u4e2a\u6587\u4ef6\u5bf9\u8c61\u65f6, \u4f7f\u7528 with<\/code><\/a> \u5173\u952e\u5b57\u662f\u975e\u5e38\u597d\u7684\u65b9\u5f0f. \u5728\u7ed3\u675f\u540e, \u5b83\u4f1a\u5e2e\u4f60\u6b63\u786e\u7684\u5173\u95ed\u6587\u4ef6, \u5373\u4f7f\u53d1\u751f\u4e86\u5f02\u5e38. \u800c\u4e14\u5199\u8d77\u6765\u4e5f\u6bd4 try<\/code><\/a> – finally<\/code><\/a> \u8bed\u53e5\u5757\u8981\u7b80\u77ed:>>> <\/strong>with<\/strong> open(‘\/tmp\/workfile’, ‘r’) as<\/strong> f: …<\/strong> read_data = f.read() >>> <\/strong>f.closed True<\/p>\n\n\n\n

    \u6587\u4ef6\u5bf9\u8c61\u6709\u4e9b\u989d\u5916\u7684\u65b9\u6cd5, \u5982 isatty()<\/code> \u548c trucate()<\/code>, \u4f46\u5b83\u4eec\u90fd\u8f83\u5c11\u7684\u4f7f\u7528; \u66f4\u591a\u7684\u4fe1\u606f\u9700\u8981\u53c2\u8003\u6807\u51c6\u5e93\u624b\u518c.<\/p>\n\n\n\n

    7.2.2. pickle<\/code><\/a> \u6a21\u5757<\/a><\/h3>\n\n\n\n

    \u5728\u6587\u4ef6\u4e2d, \u5b57\u7b26\u4e32\u53ef\u4ee5\u5f88\u65b9\u4fbf\u7684\u8bfb\u53d6\u5199\u5165. \u6570\u5b57\u53ef\u80fd\u7a0d\u5fae\u9ebb\u70e6\u4e00\u4e9b, \u56e0\u4e3a read()<\/code> \u65b9\u6cd5\u53ea\u8fd4\u56de\u5b57\u7b26\u4e32, \u6211\u4eec\u8fd8\u9700\u8981\u5c06\u5176\u4f20\u7ed9 int()<\/code><\/a> \u8fd9\u6837\u7684\u51fd\u6570, \u4f7f\u5176\u5c06\u5982 '123'<\/code> \u7684\u5b57\u7b26\u4e32\u8f6c\u4e3a\u6570\u5b57 123. \u4f46\u662f, \u5982\u679c\u8981\u4fdd\u5b58\u66f4\u590d\u6742\u7684\u6570\u636e\u7c7b\u578b, \u5982\u5217\u8868, \u5b57\u5178, \u6216\u8005\u7c7b\u7684\u5b9e\u4f8b, \u90a3\u4e48\u5c31\u4f1a\u66f4\u590d\u6742\u4e86.<\/p>\n\n\n\n

    \u4e3a\u4e86\u8ba9\u7528\u6237\u5728\u65f6\u5e38\u7684\u7f16\u7a0b\u548c\u6d4b\u8bd5\u65f6\u4fdd\u5b58\u590d\u6742\u7684\u6570\u636e\u7c7b\u578b, Python \u63d0\u4f9b\u4e86\u6807\u51c6\u6a21\u5757, \u79f0\u4e3a pickle<\/code><\/a>. \u8fd9\u4e2a\u6a21\u5757\u53ef\u4ee5\u5c06\u51e0\u4e4e\u4efb\u4f55\u7684 Python \u5bf9\u8c61 (\u751a\u81f3\u662f Python \u7684\u4ee3\u7801), \u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u8868\u793a; \u8fd9\u4e2a\u8fc7\u7a0b\u79f0\u4e3a pickling<\/em>. \u800c\u8981\u4ece\u91cc\u9762\u91cd\u65b0\u6784\u9020\u56de\u539f\u6765\u7684\u5bf9\u8c61, \u5219\u79f0\u4e3a unpickling<\/em>. \u5728 pickling \u548c unpickling \u4e4b\u95f4, \u8868\u793a\u8fd9\u4e9b\u5bf9\u8c61\u7684\u5b57\u7b26\u4e32\u8868\u793a, \u53ef\u4ee5\u5b58\u4e8e\u4e00\u4e2a\u6587\u4ef6, \u4e5f\u53ef\u4ee5\u901a\u8fc7\u7f51\u7edc\u5728\u8fdc\u7a0b\u673a\u5668\u95f4\u4f20\u8f93.<\/p>\n\n\n\n

    \u5982\u679c\u4f60\u6709\u4e00\u4e2a\u5bf9\u8c61 x<\/code>, \u548c\u4e00\u4e2a\u5df2\u7ecf\u6253\u5f00\u5e76\u7528\u4e8e\u5199\u7684\u6587\u4ef6\u5bf9\u8c61 f<\/code>, pickle \u8fd9\u4e2a\u5bf9\u8c61\u6700\u7b80\u5355\u7684\u65b9\u5f0f\u5c31\u662f\u4f7f\u7528:pickle.dump(x, f)<\/p>\n\n\n\n

    \u6709\u4e86 pickle \u8fd9\u4e2a\u5bf9\u8c61, \u5c31\u80fd\u5bf9 f<\/code> \u4ee5\u8bfb\u53d6\u7684\u5f62\u5f0f\u6253\u5f00:x = pickle.load(f)<\/p>\n\n\n\n

    (\u8fd8\u6709\u5176\u4ed6\u4e0d\u540c\u7684\u5f62\u5f0f, \u6bd4\u5982 pickling \u5f88\u591a\u5bf9\u8c61, \u6216\u8005\u4e0d\u60f3\u4fdd\u5b58\u81f3\u6587\u4ef6; \u66f4\u591a\u7684\u4fe1\u606f\u53c2\u8003 pickle<\/code><\/a> \u6a21\u5757.)<\/p>\n\n\n\n

    pickle<\/code><\/a> \u662f Python \u4e2d\u4fdd\u5b58\u53ca\u91cd\u7528\u5bf9\u8c61\u7684\u6807\u51c6\u65b9\u5f0f; \u6807\u51c6\u7684\u5c5e\u4e8e\u79f0\u4e3a persistent<\/em> \u5bf9\u8c61 (\u5373\u6301\u4e45\u5316\u5bf9\u8c61). \u56e0\u4e3a pickle<\/code><\/a> \u88ab\u5e7f\u6cdb\u4f7f\u7528, \u5f88\u591a\u5199 Python \u6269\u5c55\u7684\u4f5c\u8005\u90fd\u4f1a\u786e\u4fdd, \u5982\u77e9\u9635\u8fd9\u6837\u7684\u6570\u636e\u7c7b\u578b\u80fd\u88ab\u5408\u7406\u7684 pickle \u548c unpickle.<\/p>\n","protected":false},"excerpt":{"rendered":"

    \u6709\u591a\u79cd\u65b9\u5f0f\u53ef\u4ee5\u5c55\u73b0\u4e00\u4e2a\u7a0b\u5e8f\u7684\u8f93\u51fa; \u6570\u636e\u53ef\u4ee5\u4ee5\u4e00\u79cd\u53ef\u8bfb\u7684\u5f62\u5f0f\u8f93\u51fa, \u6216\u8005\u662f\u4fdd\u5b58\u4e8e\u4e00\u4e2a\u6587\u4ef6\u4fbf\u4e8e\u4ee5\u540e\u4f7f\u7528. \u672c\u7ae0\u5c31 […]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[],"class_list":["post-200","post","type-post","status-publish","format-standard","hentry","category-python"],"blocksy_meta":"","_links":{"self":[{"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/posts\/200","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/comments?post=200"}],"version-history":[{"count":3,"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/posts\/200\/revisions"}],"predecessor-version":[{"id":252,"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/posts\/200\/revisions\/252"}],"wp:attachment":[{"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/media?parent=200"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/categories?post=200"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/ai.gitpp.com\/index.php\/wp-json\/wp\/v2\/tags?post=200"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}