logo CodeStepByStep logo


Language/Type: PHP arrays traversals

Write a function named contains that accepts two arrays of integers $a1 and $a2 as parameters and that returns a value indicating whether or not $a2's sequence of elements appears in $a1 (true for yes, false for no). The sequence of elements in $a2 may appear anywhere in $a1 but must appear consecutively and in the same order.

For example, if variables called $a1 and $a2 store the following values:

$a1 = [1, 6, 2, 1, 4, 1, 2, 1, 8];
$a2 = [1, 2, 1];

Then the call of contains($a1, $a2) should return true because $a2's sequence of values [1, 2, 1] is contained in $a1 starting at index 5. If $a2 had stored the values [2, 1, 2], the call of contains($a1, $a2) would return false because $a1 does not contain that sequence of values. Any two arrays with identical elements are considered to contain each other, so a call such as contains($a1, $a1) should return true.


  • You may assume that both arrays passed to your function will have lengths of at least 1.
  • You may not modify either of the passed arrays.
  • You may not use any Strings to help you solve this problem, nor functions that produce Strings.

Function: Write a PHP function as described, not a complete program.

You must log in before you can solve this problem.

Log In

Need help?

Stuck on an exercise? Contact your TA or instructor.

If something seems wrong with our site, please

Is there a problem? Contact us.