php if condition with search in array values

$terreni is single dimensional array and $tuttenoterreni is multi dimensional array.

For a single dimensional array, use in_array() function and for multi dimesnional array, create a custom function to find values in this multi dimensional array.

I've provided you the following code, which will help you to find values in multi dimensional array. Follow in_array() and multidimensional array

function in_array_r($needle, $haystack, $strict = false) {
  foreach ($haystack as $item) {
    if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
      return true;
    }
  }
  return false;
}

Code:

<?php 

function in_array_r($needle, $haystack, $strict = false) {
  foreach ($haystack as $item) {
    if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
      return true;
    }
  }
  return false;
}

if (in_array(osc_item_category_id(),$terreni)) {
  echo $custom_field_value['dimensioni-terreni'] ;
} elseif(in_array_r(osc_item_category_id(), $tuttenoterreni)) {
  echo $custom_field_value['dimensioni'] ;
} else {
  echo "Oops.!! No results found.";
}?>

Useful Links:

1. in_array() - PHP Manual
2. in_array() and multidimensional array

You can't check "directly" this. You are trying to compare two type of variables.

An PHP array is a pointer to "multiple variables".

If I read your code correctly, probably your function osc_item_category_id returns an integer. In that case, the first if will change to:

<?php if (in_array(osc_item_category_id(), $terreni)) { ?>

You can check documentation about in_array function here: https://www.php.net/manual/en/function.in-array.php.

The elseif, have a similar problem. You've created a multidimensional array (an array of arrays). You need to use on this place the array_merge function (check documentation here: https://www.php.net/manual/en/function.array-merge.php), to create a unique array with all values of the another ones. Then, you can check as on the first example:

$tuttenoterreni = array_merge($appartamenti, $case, $casevacanze, $uffici, $garage, $cantine);

<?php } else if (in_array(osc_item_category_id(), $tuttenoterreni)) { ?>

if osc_item_category_id() function return no. 121,122 user this function to compare.

<?php 
    $in_id = osc_item_category_id();
    if(in_array($in_id,$terreni)){
       echo $custom_field_value['dimensioni-terreni'];
    }
?>

The in_array() function searches an array for a specific value.

Note: If the search parameter is a string and the type parameter is set to TRUE, the search is case-sensitive.

Syntax: in_array(search,array,type)

Example :

$people = array("Peter", "Joe", "Glenn", "Cleveland");
if (in_array("Glenn", $people)){
  echo "Match found";
}

Use the function bool in_array ( value , array )

this function returns true is the value is present in the array

So modify the content of if and else if condition in your code, e.g:

if(in_array(osc_item_category_id() , $terreni ))

Also what I notice in your code is that in the elseif part you are trying to compare a numerical value returned by osc_item_category_id() with the value in the 'array of array', whereas in 'if' condition you are comparing the value returned by osc_item_category_id() with value in 'array'.

If it is the fact then in elseif part you need to run a foreach loop, comparing the value returned by 'osc_item_category_id()' with each array using the above 'in_array()' method.

Hope this help out!!!