I want to search for a value in a txt file and if there is one single match then should return the number from that line

I have this in a file

blabla 21
blablabla 23
bla 29
blablabla 3
I want to search in this file for bla. If bla is found in this file should return the number 3. If I search for blablabla and is found should return 23 and so on.

Let's say that the variable $text is equal to the content you gave above.

PHP Code:

function searchFor($search, $text) {
    $text_arr = explode('\n', $text);
    foreach($text_arr as $line) {
        $split = explode(' ', $line);
        if($split[0] == $search) return $split[1];
    }
    return false;//default
}
$filename = "/path/to/something.txt";
$handle = fopen($filename, "r");
$text = fread($handle, filesize($filename));

$num = searchFor('bla', $text);//$num == 29 


This actually only works if there is only a single space per line, separating what you're searching for from the line number. If there is going to be multiple spaces in the text part, it is a bit more complicated.

$text = fread($handle, filesize($filename));

Can be dangerous on large files. You better use line-by-line reading and comparison.

If what goes into the file is something you have exact control over, and you are using it to archive information, you are far better off using a database to do so.

Data storage should always be considered on the front-end of a project... not the end.

A database system might be preferable if there is a lot of data which must be stored and queried often. Sometimes for small datasets a flat file or even a memory caching system (such as memcache or APC) is the best course of action. It really all depends.

For small datasets, I have saved a serialize array to a flat file (and memecache) in which my keys were the index that I was looking for. Yes there can be some overhead, but it has worked pretty good in certain cases.

To save file:

$a = array();
$a['blah'] = 23;
$a['blah 123'] = 1234;
$a['blahblahblah'] = 33;

$z = file_put_contents('myfile.txt', serialize($a));

To review value of 'blah'

$a = unserialize(file_get_contents('myfile.txt'));
echo $a['blah'];

I am more a fan of using this technique with memory based caching but it would work with flat files too.