Home > Backend Development > PHP Tutorial > php handles repeated lines in text document

php handles repeated lines in text document

*文
Release: 2023-03-18 14:40:01
Original
1511 people have browsed it

How does php handle repeated lines in text documents? This article mainly introduces the method of deleting duplicate lines in text files in PHP, and involves the related skills of PHP operating text files. I hope to be helpful.

The example in this article describes how to delete duplicate lines in text files in PHP. Share it with everyone for your reference. 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 = '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 == &#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));  
}
Copy after login


Usage examples:


// 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;);
Copy after login

Related recommendations:

PHP file reading fread, fgets, fgetc, file_get_contents and file function usage example code

Briefly talk about php file lock

PHP file traversal

The above is the detailed content of php handles repeated lines in text document. For more information, please follow other related articles on the PHP Chinese website!

Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template