如何使用foreach比较两个数组中的数据？

Question

i have these two feeds(feed1,feed2), they both provide some ID'S, I'm trying to find out by looping through both of them if i can match ID'S, and if their is a match don't display that ID.

foreach($feed->data as $item){
echo $item->id;
}

foreach($feed2->data as $item){
echo $item->id;
}

this is my code in PHP for displaying all of the ID's from two foreach loops, but i wanted them to be nested into each other, so if ID's in feed1 and feed2 match don't echo. so i presume their might be an if statement their somewhere. Thanks

Answer 1

$foundflag=false;
foreach($feed->data as $item){
     foreach($feed2->data as $item1){
        if($item->id == $item1->id){
           $foundflag = true;
           $array[]=$item1->id;
        }
    }
    if(!$foundflag){
        echo $item->id;
    }
}
foreach($feed2->data as $item1){
     if(!(in_array($item1->id,$array))){
        echo $item1->id;
     }
}

First nested loop will echo item id from first feed which is not present in second and second foreach will echo id from second feed which is not present in first feed

Answer 2

You could store the ID's of the one array of objects as a simple 1d array, and then whilst looping through the other feed, just check if the ID exists in the other.

# Create your variables to store the ID's of the two feeds
$ids_1 = array();
$ids_2 = array();

# Populate the arrays
foreach ($feed->data as $item1) {
    $ids_1[] = $item1->id;
}
foreach ($feed2->data as $item2) {
    $ids_2[] = $item2->id;
}

# Loop through the first feed, and exclude the items that are the same in the second
foreach($feed->data as $item){
    if (!in_array($item->id, $ids2)) {
        echo $item->id;
    }
}

# Loop through the second feed, and exclude the items that are the same in the first
foreach($feed2->data as $item){
    if (!in_array($item->id, $ids1)) {
        echo $item->id;
    }
}

Hope that helps.

Answer 3

If I understand the question right something like this should work. You might be better to do it in an array as mentioned in other questions but this should work as well.

$items;
foreach($feed->data as $item){
  echo $item->id;
  foreach($feed2->data as $item2){
    echo $item2->id;
    $pos = strrpos($items, $item2->id);
    if ($item2->id != $item->id) && ($pos == false)
      $items = $item2->id + ", ";
    }
}

echo $items;