Regex to extract string content

Question

Good evening, everyone,

Thank you for visiting and proposing to help me. I’m terrible at regex so I’ve come to ask for your help.

I have the following string that can also vary as example:

string(49) "02/12/2018 (Assessment 2) = /86= | Weight: 50.00%"
string(49) "02/12/2018 (Assessment 2) = 50.83/86= | Weight: 50.00%"

In the first case even without the amount I need to collect 00.00.

I need to extract in an array as follows:

$dados[ "date" ] = "02/12/2018"
$dados[ "markOK" ] = "50"
$dados[ "markTotal" ] = "86"
$dados[ "weight" ] = "50.00"

Other examples of output:

string(49) "02/12/2018 (Assessment 2) = /86= | Weight: 50.00%"
string(59) "06/11/2018 (Assessment 2) = 22.40/35=32.00 | Weight: 50.00%"
string(49) "04/12/2018 (Assessment 2) = /60= | Weight: 50.00%"
string(59) "11/09/2018 (Assessment 2) = 27.00/40=33.75 | Weight: 50.00%"
string(59) "09/09/2018 (Assessment 2) = 30.00/30=50.00 | Weight: 50.00%"
string(59) "14/08/2018 (Assessment 2) = 31.00/40=38.75 | Weight: 50.00%"
string(59) "19/06/2018 (Assessment 2) = 63.00/72=43.75 | Weight: 50.00%"
string(59) "17/06/2018 (Assessment 2) = 45.00/45=50.00 | Weight: 50.00%"
string(59) "22/05/2018 (Assessment 2) = 11.00/55=10.00 | Weight: 50.00%"

Answer 1

Wouldn’t use regex for that. You can break the string in array by space and make a forEach associating the values:

<?
$string = "02/12/2018 (Assessment 2) = /86= | Weight: 50.00%";
$array = explode(" ", $string);

forEach($array as $item){
   // verifica quantas barras "/" a string possui
   preg_match_all("~\/~", $item, $matches);

   // se tiver 2 barras é uma data
   if(sizeof($matches[0]) == 2){
      $dados[ "date" ] = $item;
   }

   if(sizeof($matches[0]) == 1){
      $mark = explode("/", $item);
      // se o primerio estiver vazio, retorna 00.00
      $dados[ "markOK" ] = $mark[0] ? $mark[0] : "00.00";
      $dados[ "markTotal" ] = $mark[1];
   }

   if(strrpos($item, "%")){
      $dados[ "weight" ] = str_replace("%", "", $item);
   }
}

var_dump($dados);
?>

The result is:

array(4) {
  ["date"] => "02/12/2018"
  ["markOK"] => "00.00"
  ["markTotal"] => "86="
  ["weight"]=> "50.00"
}

IDEONE

Answer 2

In your case you will need to use groups in regex to delimit and also identify what you want to search/extract, groups are identified by using elements in parentheses.

This program uses the samples you put in the question as the basis and as the regular expression became (quite) long I separated into smaller pieces so that it is easier to read and understand (as well as to adjust):

<?php

    $sampleData = array(
        "02/12/2018 (Assessment 2) = /86= | Weight: 50.00%",
        "06/11/2018 (Assessment 2) = 22.40/35=32.00 | Weight: 50.00%",
        "04/12/2018 (Assessment 2) = /60= | Weight: 50.00%",
        "11/09/2018 (Assessment 2) = 27.00/40=33.75 | Weight: 50.00%",
        "09/09/2018 (Assessment 2) = 30.00/30=50.00 | Weight: 50.00%",
        "14/08/2018 (Assessment 2) = 31.00/40=38.75 | Weight: 50.00%",
        "19/06/2018 (Assessment 2) = 63.00/72=43.75 | Weight: 50.00%",
        "17/06/2018 (Assessment 2) = 45.00/45=50.00 | Weight: 50.00%",
        "22/05/2018 (Assessment 2) = 11.00/55=10.00 | Weight: 50.00%"
    );

    $regex = '/$'.                          // começo da linha
        '([0-9]{2}\/[0-9]{2}\/[0-9]{4})'.   // 99/99/9999 (obrigatório) [1]
        ' \(Assessment.+\)'.                // " (Assessment *) " -- ignorado
        ' = '.                              // " = " -- ignorado
        '([0-9.]{5})?'.                     // 99.99 (opcional) [2]
        '\/'.                               // "/" -- ignorado
        '([0-9]{2})?'.                      // 99 (opcional) [3]
        '='.                                // "=" -- ignorado                  
        '([0-9\.]{5})?'.                    // 99.99 (opcional) [4]
        '.+Weight: '.                       // "*Weight: " -- ignorado
        '([0-9\.]{5})'.                     // 99.99 (obrigatório) [5]
        '%$/';                              // "%" e termina a linha;

    foreach ($sampleData as $i){
        preg_match($regex, $i, $matchList);
        print_r($matchList);
    }

?>

At the end, the loop foreach() at the end catches the array item by item, applies to regex and puts the result of the operation in the array $matchList.

Here [and a sample of the result:

Array
(
    [0] => 04/12/2018 (Assessment 2) = /60= | Weight: 50.00%
    [1] => 04/12/2018
    [2] => 
    [3] => 60
    [4] => 
    [5] => 50.00
)

The first item is always what was used in the query while the others are what was found and if not it will be empty.