How to change the array-key, with a simple summation?
<p>I have a simple array, whose all keys are numbered by an <em>integer</em>:</p>

<pre><code>$ArrOne = array (

"-5" =&gt; "x",
"-4" =&gt; "b",
"-3" =&gt; "s",
"-2" =&gt; "e",
"-1" =&gt; "a",
"0" =&gt; "d",
"1" =&gt; "k",
"2" =&gt; "l",
"3" =&gt; "w",
"4" =&gt; "y",
"5" =&gt; "c"

);
</code></pre>

<p>And, I have a <em>integer variable</em>, like: <code>$VarKey</code>.</p>

<hr>

<p>Now, I want to do a simple summation to all keys (of <code>$ArrOne</code>), with certain value from: <code>$VarKey</code>. The output array is: <code>$ArrTwo</code>; for instance:</p>

<ul>
<li>If <code>$VarKey = -1;</code>, <code>$ArrTwo</code> will be:</li>
</ul>

<pre>    $ArrTwo = array (

    "-6" => "x",
    "-5" => "b",
    "-4" => "s",
    "-3" => "e",
    "-2" => "a",
    "-1" => "d",
    "0" => "k",
    "1" => "l",
    "2" => "w",
    "3" => "y",
    "4" => "c"

    );</pre>

<ul>
<li><p>If <code>$VarKey = 0;</code>, <code>$ArrTwo</code> will not be changed.</p></li>
<li><p>If <code>$VarKey = +1;</code>, <code>$ArrTwo</code> will be:</p></li>
</ul>

<pre>    $ArrTwo = array (

    "-4" => "x",
    "-3" => "b",
    "-2" => "s",
    "-1" => "e",
    "0" => "a",
    "1" => "d",
    "2" => "k",
    "3" => "l",
    "4" => "w",
    "5" => "y",
    "6" => "c"

    );</pre>

<hr>

<p>How to solve this problem, with <em>PHP</em> language?</p>