PHP : Regular Expressions - [13.10] Reading Records with a Pattern Separator

13.10.1 Problem

You want to read in records from a file, in which each record is separated by a pattern you can match with a regular expression.

13.10.2 Solution

Read the entire file into a string and then split on the regular expression:

$filename = '/path/to/your/file.txt';
$fh = fopen($filename, 'r') or die($php_errormsg);
$contents = fread($fh, filesize($filename));
fclose($fh);

$records = preg_split('/[0-9]+\) /', $contents);

13.10.3 Discussion

This breaks apart a numbered list and places the individual list items into array elements. So, if you have a list like this:

1) Gödel 
2) Escher
3) Bach

You end up with a four-element array, with an empty opening element. That's because preg_split( ) assumes the delimiters are between items, but in this case, the numbers are before items:

Array
(
    [0] => 
    [1] => Gödel
    [2] => Escher
    [3] => Bach
)

From one point of view, this can be a feature, not a bug, since the nth element holds the nth item. But, to compact the array, you can eliminate the first element:

$records = preg_split('/[0-9]+\) /', $contents);
array_shift($records);

Another modification you might want is to strip new lines from the elements and substitute the empty string instead:

$records = preg_split('/[0-9]+\) /', str_replace("\n",'',$contents));
array_shift($records);

PHP doesn't allow you to change the input record separator to anything other than a newline, so this technique is also useful for breaking apart records divided by strings. However, if you find yourself splitting on a string instead of a regular expression, substitute explode( ) for preg_split( ) for a more efficient operation.