How can I get only the first two elements of an array by using a foreach loop in PHP?

If you want the first 2 by name:

Using in_array (documentation) is what you looking for:

$aMyArray = array("bmw"=>"user1", "audi"=>"user2", "mercedes"=>"user3");
$valuesToPrint = array("bmw", "audi");
foreach($aMyArray as $key => $val) {
    if (in_array($key, $valuesToPrint))
        echo "Found: $key => $val" . PHP_EOL;
}

If you want the first 2 by index use:

init index at 0 and increment in each iteration as:

$aMyArray = array("bmw"=>"user1", "audi"=>"user2", "mercedes"=>"user3");
$i = 0;
foreach($aMyArray as $key => $val) {
    echo "Found: $key => $val" . PHP_EOL;
    if (++$i > 1)
        break;
}

$counter = 1;
$max = 2;
foreach ($aMyArray as $key => $value) {
    echo $key, "=>", $value;
    $counter++;
    if ($counter === $max) {
        break;
    }
}

It is important to break execution to avoid arrays of any size looping until the end for no reason.

<?php
$aMyArray = array(
            "bmw"=>"user1",
            "audi"=>"user2",
            "mercedes"=>"user3"
);

reset($aMyArray);
echo key($aMyArray).' = '.current($aMyArray)."\n";
next($aMyArray);
echo key($aMyArray).' = '.current($aMyArray)."\n";

Easiest way:

$aMyArray=array("bmw"=>"user1","audi"=>"user2","mercedes"=>"user3");
$i=0;
foreach ($aMyArray as $key => $value) {
 if($i<2)
 {
    echo $key . 'and' . $value;
 }
 $i++;
}

I know you're asking how to do it in a foreach, but another option is using array travelling functions current and next.

$aMyArray = array(
            "bmw"=>"user1",
            "audi"=>"user2",
            "mercedes"=>"user3"
);
$keys = array_keys($aMyArray);
//current($array) will return the value of the current record in the array. At this point that will be the first record
$first = sprintf('%s - %s', current($keys), current($aMyArray)); //bmw - user1
//move the pointer to the next record in both $keys and $aMyArray
next($aMyArray);
next($keys);
//current($array) will now return the contents of the second element.
$second = sprintf('%s - %s', current($keys), current($aMyArray)); //audi - user2

You are looking for something like this

$aMyArray = array(
            "bmw"=>"user1",
            "audi"=>"user2",
            "mercedes"=>"user3"
);
foreach($aMyArray as $k=>$v){
    echo $v;
    if($k=='audi'){
        break;
    }
}