本文实例讲述了php删除文本文件中重复行的方法，分享给大家供大家参考，具体分析如下：

这个php函数用来删除文件中的重复行，还可以指定是否忽略大小写，和指定换行符：

1. /**
2. * RemoveDuplicatedLines
3. * This function removes all duplicated lines of the given text file.
4. *
5. * @param string
6. * @param bool
7. * @return string
8. */
9. function RemoveDuplicatedLines($Filepath, $IgnoreCase=false, $NewLine="\n"){
10. if (!file_exists($Filepath)){
11. $ErrorMsg = 'RemoveDuplicatedLines error: ';
12. $ErrorMsg .= 'The given file ' . $Filepath . ' does not exist!';
13. die($ErrorMsg);
14. }
15. $Content = file_get_contents($Filepath);
16. $Content = RemoveDuplicatedLinesByString($Content, $IgnoreCase, $NewLine);
17. // Is the file writeable?
18. if (!is_writeable($Filepath)){
19. $ErrorMsg = 'RemoveDuplicatedLines error: ';
20. $ErrorMsg .= 'The given file ' . $Filepath . ' is not writeable!';
21. die($ErrorMsg);
22. }
23. // Write the new file
24. $FileResource = fopen($Filepath, 'w+');
25. fwrite($FileResource, $Content);
26. fclose($FileResource);
27. }
28. /**
29. * RemoveDuplicatedLinesByString
30. * This function removes all duplicated lines of the given string.
31. *
32. * @param string
33. * @param bool
34. * @return string
35. */
36. function RemoveDuplicatedLinesByString($Lines, $IgnoreCase=false, $NewLine="\n"){
37. if (is_array($Lines))
38. $Lines = implode($NewLine, $Lines);
39. $Lines = explode($NewLine, $Lines);
40. $LineArray = array();
41. $Duplicates = 0;
42. // Go trough all lines of the given file
43. for ($Line=0; $Line < count($Lines); $Line++){
44. // Trim whitespace for the current line
45. $CurrentLine = trim($Lines[$Line]);
46. // Skip empty lines
47. if ($CurrentLine == '')
48. continue;
49. // Use the line contents as array key
50. $LineKey = $CurrentLine;
51. if ($IgnoreCase)
52. $LineKey = strtolower($LineKey);
53. // Check if the array key already exists,
54. // if not add it otherwise increase the counter
55. if (!isset($LineArray[$LineKey]))
56. $LineArray[$LineKey] = $CurrentLine;
57. else
58. $Duplicates++;
59. }
60. // Sort the array
61. asort($LineArray);
62. // Return how many lines got removed
63. return implode($NewLine, array_values($LineArray));
64. }

使用范例：

1. // Example 1
2. // Removes all duplicated lines of the file definied in the first parameter.
3. $RemovedLinesCount = RemoveDuplicatedLines('test.txt');
4. print "Removed $RemovedLinesCount duplicate lines from the test.txt file.";
5. // Example 2 (Ignore case)
6. // Same as above, just ignores the line case.
7. RemoveDuplicatedLines('test.txt', true);
8. // Example 3 (Custom new line character)
9. // By using the 3rd parameter you can define which character
10. // should be used as new line indicator. In this case
11. // the example file looks like 'foo;bar;foo;foo' and will
12. // be replaced with 'foo;bar'
13. RemoveDuplicatedLines('test.txt', false, ';');