CODEWITHSUNDEEP
phpbase64
roipoussiere
roipoussiere

Reputation: 5946

string base64 to integer/float/char array in php

I would like to convert a base64 string to other types, ie integer, float, and char array.

In Java I can use a ByteBuffer object, so it's easy to get values with methods like stream.getInt(), stream.getLong(), stream.getChar(), stream.getFloat(), etc.

But how to do this in PHP?

Edit: I tried the base64-decode PHP function, but this one decode a string, I want to decode numbers.

Edit2:

In Java:

import java.nio.ByteBuffer;
import javax.xml.bind.DatatypeConverter;

public class Main {

    public static void main(String[] args) {
        ByteBuffer stream = ByteBuffer.wrap(DatatypeConverter.parseBase64Binary("AAGdQw=="));
        while (stream.hasRemaining()) {
            System.out.println(stream.getInt());
        }
    }
}

displays 105795

But in php:

$nb = base64_decode('AAGdQw=='); // the result is not a stringified number, neither printable
settype($nb, 'int');
echo $nb;

displays 0, because base64_decode('AAGdQw==') is not printable.

Upvotes: 0

Views: 2227

Answers (2)

Franz Gleichmann
Franz Gleichmann

Reputation: 3568

you have to use unpack to convert the decoded string into a byte array, from which you then can reconstruct the integer:

<?php
$s = 'AAGdQw==';
$dec = base64_decode($s);
$ar = unpack("C*", $dec);
$i= ($ar[1]<<24) + ($ar[2]<<16) + ($ar[3]<<8) + $ar[4];

var_dump($i);
//output int(105795)

floats could be re-assembled with the pack-function, which creates a variable from a byte array.

but be advised that you have to take a lot of care about both data types AND the underlying hardware; especially the endianness (byte order) of the processor and the word size of the processor (32bit int differs from 64bit int) - therefore, if possible, you should use a text-based protocol, like JSON - which you can base64-encode, too.

Upvotes: 4

Timurib
Timurib

Reputation: 2743

Decode a content as is and cast a result to any type through type casting or some varialbe handling function such as settype().

If encoded file is large and you worried about memory consumption, you can use stream filters (relevant answer).

Upvotes: 0

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