Search only the first column of a text file - php

Question

I have a text file with the following contents:
---> 12455 ---> 125 ---> KKK
---> 11366 ---> 120 ---> LLL
---> 12477 ---> 120 ---> YYY
I am using the following PHP code to search the file for "---> 124" and I get the following results:
---> 12455 ---> 125 ---> KKK
---> 12477 ---> 120 ---> YYY
but I want the results to be like this:
---> 12455
---> 12477
I want it to return only the first column.
<?php
$file = 'mytext.txt';
$searchfor = '---> ' . "124";
// the following line prevents the browser from parsing this as HTML.
header('Content-Type: text/plain');
// get the file contents, assuming the file to be readable (and exist)
$contents = file_get_contents($file);
// escape special characters in the query
$pattern = preg_quote($searchfor, '/');
// finalise the regular expression, matching the whole line
$pattern = "/^.*$pattern.*\$/m";
// search, and store all matching occurences in $matches
if(preg_match_all($pattern, $contents, $matches)) {
echo implode($matches[0]);
} else {
echo "No matches found";
}
?>

Answer 1

Change your approach a little bit. Instead of storing the search term and separator in a single string, use two variables.
$sep = '--->';
$searchfor = '124';
$pattern = "/^$sep\s+($searchfor\d+)\s+.*/m";
// search, and store all matching occurences in $matches
if(preg_match_all($pattern, $contents, $matches)){
echo implode(' ', $matches[1])."\n";
}
Outputs:
12455 12477
Demo.

Answer 2

First of all, seperate your concerns:
Read the file
Parse the content
Search
Using Iterators, you can achieve something great here but it will need a deeper understanding of OOP and the iterator interface. What i'll recommend is a simpler approach:
<?php
//Read the file line by line
$handle = fopen('file.txt', 'r');
while(!foef($handle)){
$content = fgets($handle);
//Parse the line
$content = explode('---> ', $content);
//Analyse the line
if($content[1] == 124){
echo $content[0]."\n";
}
}
fclose($handle);
That should be it, just adapt it as you see it, i haven't tested the code here!

Answer 3

change "/^.*$pattern.*\$/m" to "/$pattern\d*/i"
and then echo implode($matches[0]); to foreach($matches[0] as $item) echo "$item<br />\r\n";

Answer 4

If the structure is always as you have shown, then:
Read the file line by line;
explode(); each line by space  ;
Read the element [1] of the result;
This seems to be most logical to me. No need for regex in here, because it will work slower then simple explode operation.
Here is an example:
$handle = fopen( 'file.txt', 'r' );
if ( $handle ) {
while ( ( $line = fgets( $handle ) ) !== false ) {
$matches = explode( ' ', $line );
if ( $matches[4] == '124' )
echo $matches[1] . '<br/>';
}
}

Answer 5

try this:
--->\s\d{5}
regex is overkill here, a simple explode('--->', $str) and selecting the first element would suffice

Answer 6

$file = file_get_contents('file.txt');
$lines = explode('---> ', $file);
for($i=1; $i<count($lines); $i=$i+3)
if(strpos($lines[$i], '124')!==false)
$col[$i/3] = /*'--> ' . */$lines[$i];
print_r($col);
That seems to work just fine. Uncomment the comment above if you want the --> included in the output. Also, the resulting $col array is indexed with the row number it is found. Just replace [$i/3] with [] if you don't want that.
Furthering this:
function SearchFileByColumn($contents, $col_num, $search, $col_count = 3) {
$segs = explode('---> ', $contents);
for($i=$col_num; $i<count($segs); $i=$i+$col_count)
if(strpos($segs[$i], $search) !== false)
$res[] = $segs[$i];
return $res;
}
$results = SearchFileByColumn($contents, 1, '124');