从php中的列表中获取特定数据

I have a string like this:

 house1- a normal house 

 house2-an office  

 house3-a scholl 

There are about 2000 lines. I want to get only house1,house2,house3 etc. from that it and put it in another file. Like:

 house1

 house2 

 house3

I understand that the explode function works for separating strings, but how can I do this?

$fContents = file( 'path/to/your/file' );
foreach ( $fContents as $row )
    file_put_contents( 'path/to/other/file', explode( '-', $row )[0] , FILE_APPEND );

Shitty but working example (assuming you got 5.4+).

for PHP 5.3:

$fContents = file( 'path/to/your/file' );
foreach ( $fContents as $row )
{
    $firstField = explode( '-', $row );
    file_put_contents( 'path/to/other/file', $firstField[0] , FILE_APPEND );
}

$str = "house1- a normal house";

$result = explode("-", $str)[0];

var_dump($result);

Assuming the latest PHP version (5.4.x).