php operation text file to delete duplicate lines-PHP Tutorial-php.cn

php operation text file to delete duplicate lines

墨辰丷

Release： 2023-03-31 14:16:01

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This article mainly introduces how to delete duplicate lines in text files using PHP. Interested friends can refer to it. I hope it will be helpful to everyone.

The example in this article describes the method of deleting duplicate lines in text files in PHP. The specific analysis is as follows:

This php function is used to delete duplicate lines in the file. You can also specify whether to ignore case and specify the newline character

/**
 * 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 = &#39;RemoveDuplicatedLines error: &#39;;
    $ErrorMsg .= &#39;The given file &#39; . $Filepath . &#39; does not exist!&#39;;
    die($ErrorMsg);
  }
  $Content = file_get_contents($Filepath);
  $Content = RemoveDuplicatedLinesByString($Content, $IgnoreCase, $NewLine);
  // Is the file writeable?
  if (!is_writeable($Filepath)){
    $ErrorMsg = &#39;RemoveDuplicatedLines error: &#39;;
    $ErrorMsg .= &#39;The given file &#39; . $Filepath . &#39; is not writeable!&#39;;  
    die($ErrorMsg);
  }
  // Write the new file
  $FileResource = fopen($Filepath, &#39;w+&#39;);   
  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 == &#39;&#39;)
      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));  
}

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Usage example:

// Example 1
// Removes all duplicated lines of the file definied in the first parameter.
$RemovedLinesCount = RemoveDuplicatedLines(&#39;test.txt&#39;);
print "Removed $RemovedLinesCount duplicate lines from the test.txt file.";
// Example 2 (Ignore case)
// Same as above, just ignores the line case.
RemoveDuplicatedLines(&#39;test.txt&#39;, 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 &#39;foo;bar;foo;foo&#39; and will
// be replaced with &#39;foo;bar&#39; 
RemoveDuplicatedLines(&#39;test.txt&#39;, false, &#39;;&#39;);

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Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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