Delete the line contains specific words/phrases with PHP

Question

I have a text file and I want to remove some lines that contain specific words

 <?php
// set source file name and path
$source = "problem.txt";

// read raw text as array
$raw = file($source) or die("Cannot read file");

now there's array from which I want to remove some lines and want to use them so on.

Answer 1

This will remove all rows that have a blacklisted word in it:

$rows = file("problem.txt");    
$blacklist = "foo|bar|lol";

foreach($rows as $key => $row) {
    if(preg_match("/($blacklist)/", $row)) {
        unset($rows[$key]);
    }
}

file_put_contents("solved.txt", implode("\n", $rows));

Or, if you are using PHP 5.3, you can use a lambda function with array_filter:

$rows = file("problem.txt");    
$blacklist = "foo|bar|lol";
$rows = array_filter($rows, function($row) {
    return preg_match("/($blacklist)/", $row);
});

file_put_contents("solved.txt", implode("\n", $rows));

Prior to PHP 5.3, a solution using array_filter would actually use up more rows than the first solution I posted, so I'll leave that out.

Answer 2

$file=file("problem.txt");
$a = preg_grep("/martin|john/",$file,PREG_GREP_INVERT );
print_r($a);

Answer 3

Check out the strpos function. It can tell you if a string contains another string or not (and where exactly the first string is in the second). You would use it like this:

$good = array();
$bad_words = array('martin', 'methew');

// for every line in the file
foreach($raw as $line) {
  // check for each word we want to avoid
  foreach($bad_words as $word) {
    // if this line has a trigger word
    if(strpos($line, $word) !== false) {
      // skip it and start processing the next
      continue 2;
    }
  }

  // no triggers hit, line is clean
  $good[] = $line;
}

Now you would have a list of only clean lines in $good.

Answer 4

If you have a long string rather than a file and you want to remove all string lines that has specific words. You can use this:

$string="I have a long string\n
  That has good words inside.\n
   I love my string.\n
  //add some words here\n";
$rows = explode("\n",$string);
$unwanted = "tring|\/\/";
$cleanArray= preg_grep("/$unwanted/i",$rows,PREG_GREP_INVERT);
$cleanString=implode("\n",$cleanArray);
print_r ( $cleanString );

This removes that has lines contain "tring" and "//".

Answer 5

Assuming that you have an array of "bad words":

<?php
foreach ($raw as $key=>$line)
{
    foreach ($badwords as $w)
    {
        if ( strpos($line, $w) !== false )
            unset($raw[$key]);
    }
}
?>

Answer 6

<?php
$source = "problem.txt";
$raw = file_get_contents($source) or die("Cannot read file");
$wordlist = "martin|methew";
$raw = preg_replace("/($wordlist)/i", "", $raw);
file_put_contents($source, $raw);
?>