- array_combine: documentation ( source)
- print_r: documentation ( source)
- preg_match_all: documentation ( source)
<?php
$re = '~<(\d+)>\h*(\d+(?:\.\d+)?)\h*</\h*\1>~m';
$str = '<5> 20825.24 </ 5> <7> 0.0 </ 7> <8> 0.0 </ 8>';
preg_match_all($re, $str, $matches);
print_r(array_combine($matches[1], $matches[2]));