PHP - How to sort the same array multiple times?

I am trying to make a simple script that will first put an array() into function so I can call on it multiple times to sort. Here is what my array looks like:

// I want this inside of a function so I can call on it:

$a = array(
    15 => "C",
    12 => "E",
    11 => "B",
    19 => "P",
    10 => "L",
    14 => "N",
    20 => "A"    
 );

// This is how I brought it into a function and formatted it:

function original_array($a){ 
    foreach($a as $key => $types) {
        print $key . " " . ":" . " " . $types . "<br />";
    }
}

I then just have to call original_array() and it prints out fine, but if I sort it once I cant sort it again. It will just print out the first sort:

// Print out array is is:

original_array();

// Then I print out array with sort():

sort($a);
original_array($a);

// But if I try and sort it again with different sort it doesn't work:

ksort($a);
original_array($a);

What am I doing wrong? I am somewhat new to PHP so your help is greatly appreciated.

UPDATE://

This is what I ended up doing. I should have read up on sort function a little more thoroughly. I was unaware that it destroyed the original pointers.

<?php  
// Original array: 
$a = array(
    15 => "C",
    12 => "E",
    11 => "B",
    19 => "P",
    10 => "L",
    14 => "N",
    20 => "A"   
);

// Array for sort() function:
$b = $a

function print_format($array){ 
    foreach($array as $key => $types) {
        print $key . " " . "=>" . " " . $types . "<br />";
    }
}    


print "Original";  
print_format($a);     

print "sort()";
sort($b);
print_format($b);

print "ksort()";
ksort($a);
print_format($a);    

print "asort()";
asort($a);  
print_format($a);    

print "krsort()";
krsort($a);  
print_format($a);

print "rsort()";
rsort($b);  
print_format($b);    

print "arsort()";
arsort($a);  
print_format($a);
?>