Question

This is a simple problem but I’m wasting too much time trying to figure it out on my own.

I had data stored in strings with the pattern r{N}-{N}s{N} where {N} is a one or two digit number. This pattern can repeat up to 5 times. I need to extract the numbers from the pattern, preferably grouped somehow.

For example, if the string were "r4-10s5", I want to extract {4,10,5}

If the string were "r4-10s5r6-7s8" I want to extract {4,10,5} {6,7,8}

How could I get this done in PHP?

I have tried using recursive regular expressions but I cannot get them to match properly.

Answer 1

$str = "r4-10s5r6-7s8";

preg_match_all("#r(\d{1,2})-(\d{1,2})s(\d{1,2})#", $str, $matches);

// group the matches together
$sets = array();
for ($i = 0, $count = count($matches[0]); $i < $count; $i++)
    $sets[] = array($matches[1][$i], $matches[2][$i], $matches[3][$i]);

print_r($sets);

Outputs:

array (size=2)
  0 => 
    array (size=3)
      0 => string '4' (length=1)
      1 => string '10' (length=2)
      2 => string '5' (length=1)
  1 => 
    array (size=3)
      0 => string '6' (length=1)
      1 => string '7' (length=1)
      2 => string '8' (length=1)

---

Another option that doesn’t have the loop would be:

preg_match_all("#r(\d{1,2})-(\d{1,2})s(\d{1,2})#", $str, $matches, PREG_SET_ORDER);

print_r($matches);

Outputs:

array (size=2)
  0 => 
    array (size=4)
      0 => string 'r4-10s5' (length=7)
      1 => string '4' (length=1)
      2 => string '10' (length=2)
      3 => string '5' (length=1)
  1 => 
    array (size=4)
      0 => string 'r6-7s8' (length=6)
      1 => string '6' (length=1)
      2 => string '7' (length=1)
      3 => string '8' (length=1)