PHP find last occurrence from multidimensional array from given index

Question

Is it possible to find the last occurrence of a value in an array element starting at a specific index value. I have found a partial solution in this post [How can I find the key of the last occurrence of an item in a multidimensional array? but it doesn't allow for starting at a specific index. I am looping thru an array matching an 'id' number. If the 'id' number doesn't exist in the current array index, I would like to search back from that point finding the last occurrence of that value.

 $last = "";
  foreach($arr as $key => $array) {
    if ( $array['id'] === $id) {
    $last = $key;
   }
   }
  echo $last."\n\n";

is $arr has numerical indexes?

splash58
– splash58

2016-05-20 18:01:59 +00:00
Commented May 20, 2016 at 18:01 — splash58
– splash58, Commented May 20, 2016 at 18:01

splash58 · Accepted Answer · 2016-05-20 20:50:52Z

1

If the array has numeric indexes, you can do that with usual for loop

$last = false;
for($i = $start; $i >= 0; $i--) {  // $start - index to start look up
  if ( $arr[$i]['id'] === $id) {
     $last = $i; 
     break;                        // if key is found, stop loop
  }
}

if($last !== false)
  echo $last."\n\n";
else
  echo "Not found" . "\n";

edited May 20, 2016 at 20:50

answered May 20, 2016 at 18:08

splash58

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2 Comments

snowman Over a year ago

Works great with one problem, would there be a reason the found last index would be 1 off. When executed and I review the values of the array at the $last, they are 1 off or showing the values for the next array. If I use $last-1 it skips the desired array and grabs the values of the one before it.

splash58 Over a year ago

@snowman i was writing by phoe and made many mistakes. Test it now

JustLloyd · Accepted Answer · 2016-05-20 18:00:25Z

0

<?php

$myArray = [
  "bus" => "blue",
  "car" => "red",
  "shuttle" => "blue",
  "bike" => "green";
];

$findValue = "blue";

$startIndex = "bus";
$continue = false;
$lastIndex = null;

foreach ($myArray as $key => $value) 
{
  if(!$continue && $key === $startIndex) 
  {
    $continue = true;
  } else if($continue) {
    if($key === $findValue) {
      $lastIndex = $key;
    }
  }
}

Basically what I'm doing here is only checking the index against first index you're trying to find, if its found that index it'll go on to try and compare the current key's value to the one you're trying to specify.

answered May 20, 2016 at 18:00

JustLloyd

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