How to print array element with keys & values in PHP?

Question

I'm learning array and loop in php. But can't print the array with keys & values. How can I do this?

<?php
$marks = array (
    "Alice" => array (
        "physics" => "60",
        "math" => "65"
    ),
    "Bob" => array (
        "physics" => "40",
        "math" => "45"
    )
);

foreach ( $marks as $key => $value) {
    foreach ( $key as $key2 => $value2 ) {
        echo $key . " : " . $key2 . " - " . $value2 . "<br>";
    };
};
?>

Answer 1

In the nested foreach you have to iterate over the $value which holds the array.

foreach ( $marks as $key => $value) {
   foreach ( $value as $key2 => $value2 ) {
   // -------^^^^^^-------
      echo $key . " : " . $key2 . " - " . $value2 . "<br>";
   }
};

Answer 2

Use this

foreach ( $marks as $key => $value) {
     foreach ( $value as $key2 => $value2 ) {
        echo $key . " : " . $key2 . " - " . $value2 . "<br>";
          }
       }

Answer 3

This way it could be more readable to fix it and clear up confusion:

     $marks = array(
        'Alice' => array(
            'physics' => 60,
            'math' => 65,
        ),
        'Bob' => array(
            'physics' => 40,
            'math' => 45,
        ),
    );

    // Loop students
    foreach($marks as $name => $grades){

        // Loop their grades
        foreach ($grades as $subject => $score){
            echo $name . ' : ' . $subject . ' - ' . $score . '<br>';
        }
    }

Please note that the numbers are without quotes. This will allow you to use them as numbers to do further calculations.