The following function searches for an item $search_item form an array $data_array by going through each items of the array. If item found in the $data_array array then it returns the index number of that item, otherwise it returns -1;
$data_array = [1,4,23,33,2,56,11,44,22,76,200,3];
$search_item = 11;
function linear_search( $data_array, $search_item ){
for( $i = 0; $i < count($data_array); $i++ ){
if( $data_array[$i] == $search_item ){
return $i;
}
}
return -1;
}
$itm_indx = linear_search( $data_array, $search_item );
if( $itm_indx > 0 ){
echo 'item found in index = '.$itm_indx;
}else{
echo 'item not found';
}