php删除文本文件中重复行的方法

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

/**

* RemoveDuplicatedLines

* This function removes all duplicated lines of the given text file.

*

* @param string

* @param bool

* @return string

*/

function RemoveDuplicatedLines($Filepath, $IgnoreCase=false, $NewLine="n"){

if (!file_exists($Filepath)){

$ErrorMsg = 'RemoveDuplicatedLines error: ';

$ErrorMsg .= 'The given file ' . $Filepath . ' does not exist!';

die($ErrorMsg);

}

$Content = file_get_contents($Filepath);

$Content = RemoveDuplicatedLinesByString($Content, $IgnoreCase, $NewLine);

// Is the file writeable?

if (!is_writeable($Filepath)){

$ErrorMsg = 'RemoveDuplicatedLines error: ';

$ErrorMsg .= 'The given file ' . $Filepath . ' is not writeable!';

die($ErrorMsg);

}

// Write the new file

$FileResource = fopen($Filepath, 'w+');

fwrite($FileResource, $Content);

fclose($FileResource);

}

/**

* RemoveDuplicatedLinesByString

* This function removes all duplicated lines of the given string.

*

* @param string

* @param bool

* @return string

*/

function RemoveDuplicatedLinesByString($Lines, $IgnoreCase=false, $NewLine="n"){

if (is_array($Lines))

$Lines = implode($NewLine, $Lines);

$Lines = explode($NewLine, $Lines);

$LineArray = array();

$Duplicates = 0;

// Go trough all lines of the given file

for ($Line=0; $Line < count($Lines); $Line++){

// Trim whitespace for the current line

$CurrentLine = trim($Lines[$Line]);

// Skip empty lines

if ($CurrentLine == '')

continue;

// Use the line contents as array key

$LineKey = $CurrentLine;

if ($IgnoreCase)

$LineKey = strtolower($LineKey);

// Check if the array key already exists,

// if not add it otherwise increase the counter

if (!isset($LineArray[$LineKey]))

$LineArray[$LineKey] = $CurrentLine;

else

$Duplicates++;

}

// Sort the array

asort($LineArray);

// Return how many lines got removed

return implode($NewLine, array_values($LineArray));

}

使用范例：

// Example 1

// Removes all duplicated lines of the file definied in the first parameter.

$RemovedLinesCount = RemoveDuplicatedLines('test.txt');

print "Removed $RemovedLinesCount duplicate lines from the test.txt file.";

// Example 2 (Ignore case)

// Same as above, just ignores the line case.

RemoveDuplicatedLines('test.txt', true);

// Example 3 (Custom new line character)

// By using the 3rd parameter you can define which character

// should be used as new line indicator. In this case

// the example file looks like 'foo;bar;foo;foo' and will

// be replaced with 'foo;bar'

RemoveDuplicatedLines('test.txt', false, ';');

希望本文所述对大家的php程序设计有所帮助。