file_get_contents + preg_match > find a line starting with a word

Question

I do a file_get_contents to get a long file and I would like to find the line (there is only one) which starts with "MyParam" (for example). I don't want to cut the file line by line, I want to do it with a preg_match only (or equivalent). I've tried many things but no success. Thanks in advance

FILE CONTENT

//some text
//some text
//MyParam "red"
//some text
MyParam "blue"
Some text
// Some text

And I would like to get MyParam "blue" only.

Show what you have tried please, also a sample of input is appreciated — HamZa, May 05 '14 at 15:13
Question understood partially... Can you post your input and expected output ? — Shankar Narayana Damodaran, May 05 '14 at 15:14
Related: [Search String and Return Line PHP](https://stackoverflow.com/q/9721952/2943403) — mickmackusa, Apr 28 '23 at 11:30

Amal Murali · Accepted Answer · 2014-05-05T15:34:06.063

4

If you must use a regex, you can do it as follows:

preg_match('/^MyParam[^\r\n]*/m', $text, $matches);
var_dump($matches[0]);

Explanation:

[^\r\n] - a character class that matches any characters other than a \r or \n.
m - multiline modifier, which changes the meaning of ^ from "assert position at the beginning of the string" to "assert position at the beginning of each line".

Here, $matches[0] will contain the complete matched string (which in this case, is what you want).

Output:

string(14) "MyParam "blue""

Demo

edited May 05 '14 at 15:34

answered May 05 '14 at 15:23

Amal Murali

75,622
18
128
150

@HamZa: wouldn't that include the newline as well? See here: https://eval.in/146768 – Amal Murali May 05 '14 at 15:28
3

Be creative and use `[^\r\n]*` :P – HamZa May 05 '14 at 15:29
It works. Thanks. `preg_match` is really slow, or it's ok to do like that ? – Peter Estiven May 05 '14 at 15:40
@Peter: I'd say it depends on the length of your string. If the string is very long, I'd go with Casmir's solution as it reads line by line. In this case, it shouldn't really matter though. – Amal Murali May 05 '14 at 15:42
@AmalMurali the file has around 1000 lines. – Peter Estiven May 05 '14 at 15:46
Thanks for the 'm' modifier! Saved some pulled follicles. :D – Brian Fegter Mar 23 '17 at 18:16

Casimir et Hippolyte · Answer 2 · 2014-05-05T15:33:52.583

Using file_get_contents is not the best choice here since you can read the file line by line

$handle = fopen("yourfile.txt", "r");
if ($handle) {
    while (($line = fgets($handle)) !== false) {
        if (strpos($line, 'MyParam')===0) {
            echo 'found';
            break;
        }
    }
} else {
    echo 'error opening the file';
} 
fclose($handle);

Note: if you need to extract a parameter value between quotes you can use:

$value = explode('"', $line, 3)[1];

score 2 · Answer 3 · answered May 05 '14 at 15:18

No need of regexp:

$pos = strpos($filecontent, "\nMyParam");
$endline = strpos($filecontent, "\n", $pos + 1);
$line = substr($filecontent, $pos + 1, $endline - $pos - 1) ;

Not tested, there is maybe an offset of +-1 in the string but it gives you the idea.

Edit : If you are sure that "MyParam" does not appears elsewhere in the file, you can remove the first "\n".

score 1 · Answer 4 · answered May 05 '14 at 15:16

1

You could use strpos() to find the position of the first occurrence of a substring in a string.

http://nl1.php.net/strpos

answered May 05 '14 at 15:16

R Pelzer

1,188
14
34

Mike Brant · Answer 5 · 2014-05-05T15:55:21.107

I would consider a couple of different approaches here. The most important thing to consider is that you don't need to read the entire file into memory via file_get_contents(). I would be inclined to just use shell commands to do this:

$file = '/path/to/file';
$search_pattern = '^MyParam';
$file_safe = escapeshellarg($file);
$pattern_safe = escapeshellarg($search_pattern);
$result = exec('grep ' . $pattern_safe . ' ' . $file_safe);

Alternately, you can read through the file one line at a time looking for the match:

$result = '';
$file = '/path/to/file';
$search = 'MyParam'; // note I am not using regex here as this is unnecessary in your case
$handle = fopen($file, 'r');
if ($handle) {
    while($line = fgets($handle) !== false) {
        if (strpos($line, $search) === 0) { // exact match is important here
            $result = $line;
            break;
        }
    }
    fclose($handle);
}

file_get_contents + preg_match > find a line starting with a word

5 Answers5