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
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/**
* 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,$NewLine="\n"){
if (is_array($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：
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// 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。
