Counting, highlighting and printing the duplicates between two arrays - php

Question

First time posting on stackoverflow.
After printing the main array, I have managed to highlight the values that are found in the second one, but I also want to print the number of times that the duplicate occurs in brackets at the same time. I have run out of the ideas on how to do that last part, I get stuck in multiple loops and other problems. I will paste here what's working for now.
The code:
$main = array( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20 );
$secondary = array( 1, 6, 10, 6, 17, 6, 17, 20 );
foreach ( $main as $number )
{
if ( in_array( $number, $secondary ) )
{
echo $item;
// this one is supposed to be highlighted, but the html code disappears on stackoverflow
/* this is where the number of duplicates should appear in bracket, example:
highlighted number( number of duplicates ) */
}
else
{
echo $item;
// this one is simple
}
}
EXPECTED RESULT:
1(1), 2, 3, 4, 5, 6(3), 7, 8, 9, 10(1), 11, 12, 13, 14, 15, 16, 17(2), 18, 19, 20(1)
Basically the brackets contain the number of times that the value is found in the second array, aside from being colored, but I can't paste the html code for some reason. Sorry for not making the expected result more clear !
PROBLEM SOLVED:
Thanks to everyone for your help, first time using this website, didn't expect such a quick response from you guys. Thank you very much !

Answer 1

You need to get the count values of your secondary array first using array_count_values. This is what you can acquire as
$main = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20);
$secondary = array(1, 6, 10, 6, 17, 6, 17, 20);
$count_values = array_count_values($secondary);
foreach ($main as $key => $value) {
if (in_array($value, $secondary)) {
echo $value . "<strong>(" . $count_values[$value] . ")</strong>";
echo ( ++$key == count($main)) ? '' : ',';
} else {
echo $value;
echo ( ++$key == count($main)) ? '' : ',';
}
}
Output:
1(1),2,3,4,5,6(3),7,8,9,10(1),11,12,13,14,15,16,17(2),18,19,20(1)

Answer 2

Assuming $secondary is the one with the dupes, you should go about it the other way:
$dupes = array();
foreach($secondary as $number) {
if (in_array($number, $main)) {
$dupes[$number]++;
}
}
var_dump($dupes);

Answer 3

<?php
$main = array( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17,18,19,20);
$secondary = array( 1, 6, 10, 6, 17, 6, 17, 20 );
$result =array();
foreach($main as $key => $value){
$i=0;
foreach($secondary as $key1 => $value1){
if($value == $value1){
$i++;
}
$result[$value] = $i;
}
}
$resultString ='';
foreach($result as $key => $value){
$resultString .=$key.'('.$value.'),' ;
}
echo trim($resultString,',');
?>
Result:
1(1),2(0),3(0),4(0),5(0),6(3),7(0),8(0),9(0),10(1),11(0),12(0),13(0),14(0),15(0),16(0),17(2),18(0),19(0),20(1)