拆分字符串[关闭]

Question

I have created an encryption algorithm in which I need to reverse, I need to separate a string into pairs of 3 into an array, I have looked all over and have found no help, how would I do this?

Edit: I have tried:

<?php
$todecode="#number too big to post#";
$len=strlen($todecode);
$a=0;
$b=array();
While($len!=$a){
//$decoded=chunk_split($todecode);
$add1=$todecode[$a];
$a=$a+1;
$add2=$todecode[$a];
$a=$a+1;
$add3=$todecode[$a];
$a=$a+1;
$adder=$add1,$add2,$add3;
array_push($b,$adder);
}

But nothing else yet.

Answer 1

    $num_str = "12312312315234535";
    print_r(str_split($num_str,3));