PHP Compare Array

PHP - Check if two arrays are equal

$arraysAreEqual = ($a == $b); // TRUE if $a and $b have the same key/value pairs.
$arraysAreEqual = ($a === $b); // TRUE if $a and $b have the same key/value pairs in the same order and of the same types.

See Array Operators.

EDIT

The inequality operator is != while the non-identity operator is !== to match the equality
operator == and the identity operator ===.

Compare array items against other items in array one time

You could use two for loops

$count = count($z);
for ($i = 0; $i < $count - 1; $i++) {
    for ($j = $i + 1; $j < $count; $j++) {
        // compare $z[$i] with $z[$j]...
    }
}

The other loop goes from 0 to n - 2 and the inner loop takes the value from the outer value as initial and goes to the end.

If you also need to handle associative arrays, like one commenter mentioned, you could use array_values (and array_keys) to handle this case.

$values = array_values($z);
$keys = array_keys($z); // optional - only used, if you need the keys..
$count = count($values);
for ($i = 0; $i < $count - 1; $i++) {
    for ($j = $i + 1; $j < $count; $j++) {
        // compare $values[$i] with $values[$j]...
        // or $keys[$i] with $keys[$j];
    }
}

Note: A foreach loop won't work in either case, because you can't
told the inner loop to skip all values, already seen in the outher
loop. And teaching the foreach loop this behavior would result in a
foreach, that effectly looks like a simple for loop and is slower.
There's simply no benefit in using a foreach.

PHP compare 2 arrays and get only the non matching values

array_diff — Computes the difference of arrays

$array1 = array("verbal aggression", "physical aggression", "vol");
$array2 = array("verbal aggression", "physical aggression");

$result=array_diff($array1,$array2);
print_r($result);

Output :

Array
(
    [2] => vol
)

PHP compare two arrays of dates and check for match

You can do it this way too:

$result_array = array();
$found = false;
for($i=0; $i<count($vacation_array); $i++) {
  $found = false;
  for($j=0; $j<count($vacation_array[$i]['days']); $j++) {
    if(in_array($vacation_array[$i]['days'][$j], $array_1) && !$found) {
      $result_array[] = $vacation_array[$i];
      $found = true;
    }
  }
}
print_r($result_array);

Compare two array and get all differences

try this

array_merge(array_diff($array1,$array2),array_diff($array2,$array1))

Compare multidimensional array with another array in PHP and get the values from the multidimensional array

For your example data, you could use array_reduce and use in_array to check if the tag is present in $compare_array

If you must make a variable with the name from the $compare_array and append the value to the variable you might use extract with a flag that suits your expectations.

The value is not present in all the example data so you might also check if that exists.

$compare_array = array('DOCUMENT', 'SENDERID', 'SENDERSHORTNAME', 'RECIPIENTID');
$result = array_reduce($arrays, function($carry, $item) use ($compare_array) {
    if(isset($item["value"]) && in_array($item["tag"], $compare_array, true)) {
        $carry[$item["tag"]] = $item["value"];
    }
    return $carry;
});
extract($result, EXTR_OVERWRITE);

echo $SENDERID;
echo $RECIPIENTID;

Demo

Compare Positions of Values in Php Array

Here is a demonstration with a battery of test cases to fully express how it works and identify fringe cases: (Demo Link)

*note, array_search() returns false when the needle is not found.

$commands = array("mark", "ignore", "pick", "random");

$attempts = array("mark", "ignore", "pick", "random", "bonk");
foreach($attempts as $attempt){
    echo "$attempt => ";
    $index=array_search($attempt,$commands);
    //                                    vv---increment the value
    if($index===false || !isset($commands[++$index])){  // not found or found last element
        $index=0;                                      // use first element
    }
    echo $commands[$index],"\n";
}

The "or" (||) condition will "short circuit", so if $index is false it will exit the condition without calling the second expression (isset()).

Output:

mark => ignore
ignore => pick
pick => random
random => mark
bonk => mark