检查数组中的值是否与另一个爆炸值重复

Question

hello try to find the duplicated value in array i have array like that

$array = array('1%2','3%4','1%2',1%3);

so i want to find duplicated 2 after % so i used explode inside foreach

foreach($array as $value){
   $s = explode('%',$value);
   if($s[1] == $s[1]){
    echo 'there are duplicated 2';
   }
}

so i want $s[1] check if value after % in array is duplicated is there anyway to do that

Answer 1

You will need to collect the right side values as you loop through them and check for duplicates. I am accessing the strings' right side values via their "offset" [2]. When found, you can exit the loop with a break.

Code: (Demo)

$array=['1%2','3%4','1%2','1%3'];
$kept=[];
foreach($array as $i=>$v){
    if(in_array($v[2],$kept)){
        echo "Element (index $i) containing $v has duplicate right side value.";
        break;
    }
    $kept[]=$v[2];
}

Output:

Element (index 2) containing 1%2 has duplicate right side value.

---

If you want to search for all element that end with %2, you can use preg_grep().

Code:

$search=2;
$array=['1%2','1%3','1%4','3%2','5%2'];
var_export(preg_grep("/%{$search}$/",$array));

Output:

array (
  0 => '1%2',
  3 => '3%2',
  4 => '5%2',
)

---

Or without regex, it will require more function calls:

$search=2;
$array=['21%2','1%3','2%22','1%4','3%21','5%2'];
var_export(array_filter($array,function($v)use($search){return strpos($v,"%$search")+2===strlen($v);}));

Output:

array (
  0 => '21%2',
  5 => '5%2',
)

---

...[deep breath] Here is attempted answer #4...

Code:

$array=['1%2','1%3','1%4','3%2','5%2'];
foreach($array as $v){
    $grouped[explode('%',$v)[1]][]=$v;  // use right side number as key
}
var_export($grouped);

Output:

array (
  2 => 
  array (
    0 => '1%2',
    1 => '3%2',
    2 => '5%2',
  ),
  3 => 
  array (
    0 => '1%3',
  ),
  4 => 
  array (
    0 => '1%4',
  ),
)

---

If you want to count the right side values in the array:

$array=['1%2','1%3','1%4','3%2','5%2'];
$array=preg_replace('/\d+%/','',$array);  // strip the left-size and % from elements
var_export(array_count_values($array));  // count occurrences

Output:

// [right side values] => [counts]
array (
  2 => 3,
  3 => 1,
  4 => 1,
)