PHP how to limit lines in a string ?

Question

Hi, i have a variable like the following and i want a function to only keep the first 20 lines, so it will strips any additional \n lines more than 20.

<?php
$mytext="Line1
Line2
Line3
....."

keeptwentyline($mytext);
?>

Answer 1

I suppose a (maybe a bit dumb ^^ ) solution would be to :

• explode the string into an array of lines
• keep only the X first lines, using, for instance, array_slice
• implode those back into a string.

Something like that would correspond to this idea :

var_dump(keepXlines($mytext, 5));

function keepXLines($str, $num=10) {
    $lines = explode("\n", $str);
    $firsts = array_slice($lines, 0, $num);
    return implode("\n", $firsts);
}

Note : I passed the number of lines as a parameter -- that way, the function can be used elsewhere ;-)
And if the parameter is not given, it takes the default value : 10

But there might be some clever way ^^

(that one will probably need qiute some memory, to copy the string into an array, extract the first lines, re-create a string...)

Answer 2

function keeptwentyline( $string )
{
     $string = explode( "\n", $string );
     array_splice( $string, 20 );
     return implode( "\n", $string );
}

Or (probably faster)

function keepLines( $string, $lines = 20 )
{
    for( $offset = 0, $x = 0; $x < $lines; $x++ ) {
        $offset = strpos( $string, "\n", $offset ) + 1;
    }

    return substr( $string, 0, $offset );
}