Push item into an array and replace php - php

Question

i need to make an array like this
$privateMsgIdArray = array("idlistener" => $idlistener, "maxMsgId" => $lastMsgId);
I need to replace the maxMsgId to the corresponding idlistener, and if the idlistener that i pass doesn't not exist to create a new entry inside the array.
I am a but confused on how i am going to extract the maxMsgId value corresponding to an idlistener.
In other words i need to pass new values of idlisteners only once, and replace maxMsgId each time that they are not equal to the corresponing idlistener.
If the idlistener field doesn't exist create it (push into array).
I pass old array into a session and new array in the current run.
After the run i i replace them.
I believe this sounds a bit confusing though.
e.g
We have an array like this already:
[15][200]
next call maxMsgId is 210
array should be
[15][210]
next call we have a new listener id with maxMsgId 30
array should be
[15][210]
[16][30]

Answer 1

You should be able to accomplish this with a quick loop:
// your "new" values
$idListener = 15;
$maxMsgId = 210;
// loop over the array to see if it contains the `idlistener` you want
$end = count($privateMsgIdArray);
for ($i = 0; $i < $end; $i++) {
if ($privateMsgIdArray[$i]['idlistener'] == $idListener) {
// we found it! overwrite the `maxMsgId` field
$privateMsgIdArray[$i]['maxMsgId'] = $maxMsgId;
break;
}
}
if ($i == $end) {
// we reached the end of the array without finding the `$idListener`;
// add a new entry =]
$privateMsgIdArray[] = array(
'idlistener' => $idListener,
'maxMsgId' => $maxMsgId
);
}
This is a rather brute-force approach though and, if efficiency is something you're after, it would be wise to create a "cache"-style method of idlistener values and their index in the $privateMsgIdArray array.
For instance:
// key = idlistener, value = index in `$privateMsgIdArray`
$idCache = array(15 => 0, 16 => 1);
// check if the `$idListener` is in the cache
if (!isset($idCache[$idListener])) {
// it's not; add a new entry
$key = count($privateMsgIdArray);
$privateMsgIdArray[$key] = array(
'idlistener' => $idListener,
'maxMsgId' => $maxMsgId
);
// add the new index into the cache
$idCache[$idListener] = $key;
} else {
// it is in the cache; pull the corresponding index and set the `maxMsgId` =]
$privateMsgIdArray[$idCache[$idListener]]['maxMsgId'] = $maxMsgId;
}
Both of the approaches above could be converted into functions to make things "more portable" too.