How to convert base64 index to plain string in PHP?

$let = chr(bindec($let));

It returns : 

I need to convert to String.

foreach($binaryArray as $binary){
        $let = str_pad($binary, 6, 0, STR_PAD_RIGHT);
        //$let = bindec($let);
        $let = chr(bindec($let));
        $base64String .= $let;
    }

CodePudding user response：

Ah, looking at the Base64 table in Wikipedia it starts to make sense to me. I think it can be as simple as this:

$binaryArray = [19,16];        
$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 /";
$base64String = "";
foreach ($binaryArray as $index) {
    $base64String .= $chars[$index];
}
echo $base64String;

This does return "TQ". See: PHP fiddle