view binary values

Question

I have binary stored in string

$str = "100001111111110000101010100010000001";

that I get from converting numbers array

$arrAsc = Array
(
    [0] => 33
    [1] => 63
    [2] => 48
    [3] => 42
    [4] => 34
    [5] => 1
)
$arrBinary = array_map(create_function('$a', 'return decbin($a);'), $arrAsc);

after breaking the value out into 6-bit chunks I have

Array
(
    [0] => 100001
    [1] => 111111
    [2] => 110000
    [3] => 101010
    [4] => 100010
    [5] => 1
)

my question is how to show zeros first even if there 5,6,7.... bit chunks

Array
(
    [0] => 100001
    [1] => 111111
    [2] => 110000
    [3] => 101010
    [4] => 100010
    [5] => 000001
)

@Jeff Pigarelli I prepare myself to php exam. try to build base64_decode() for better understanding php — qpaycm
– qpaycm, Commented Mar 1, 2012 at 0:04

Freyja · Accepted Answer · 2012-03-01 00:11:11Z

2

You can use array_map() and str_pad() to add leading zeroes to each string. If you want only the last 6 bits (in cases where there might be 7 or more bits), you might also want to use substr():

<?
// Create our array
$chunks = array('100001', '111111', '110000', '101010', '100010', '1');

// Apply an anonymous function to each chunk
$chunks = array_map(
  function($x) {
    // Get only 6 last bits (might not be necessary, depending on your needs)
    $x = substr($x, -6);
    // Add leading zeroes
    $x = str_pad($x, 6, '0', STR_PAD_LEFT);
  },
  $chunks
);

print_r($chunks);
// Array
// (
//     [0] => 100001
//     [1] => 111111
//     [2] => 110000
//     [3] => 101010
//     [4] => 100010
//     [5] => 000001
// )

edited Mar 1, 2012 at 0:11

answered Mar 1, 2012 at 0:04

Freyja

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Comments

leemeichin · Accepted Answer · 2012-03-01 00:11:31Z

1

To expand on Frxstrem's (first) answer, this can be done in one go, without using array_map to first convert the numbers, and then again to pad them:

$arrAsc = array(33, 63, 48, 42, 34, 1);

$array_binary = array_map(function($dec) {
    return str_pad(decbin($dec), 6, '0', STR_PAD_LEFT);
}, $arrAsc);

Array
(
  [0] => 100001
  [1] => 111111
  [2] => 110000
  [3] => 101010
  [4] => 100010
  [5] => 000001
)

answered Mar 1, 2012 at 0:11

leemeichin

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Comments

Community · Accepted Answer · 2023-11-20 22:45:59Z

0

What you are really asking to do is pad a string with leading zeros.

Use something like:

$paddedString = str_pad($oldString, 6, '0', STR_PAD_LEFT);

This would obviously be suitable for use in an array_map(), which you already know how to use.

edited Nov 20, 2023 at 22:45

CommunityBot

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answered Mar 1, 2012 at 0:04

Conrad Shultz

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Comments

pifantastic · Accepted Answer · 2012-03-01 00:05:47Z

0

You can use printf to format the string:

<?php

$str = "1111111000011010101001000000011";
$words = array();

foreach (str_split($str, 6) as $word) {
    $words[] = sprintf("%06s", $word);
}

print_r($words);

Which will output:

Array
(
    [0] => 111111
    [1] => 100001
    [2] => 101010
    [3] => 100100
    [4] => 000001
    [5] => 000001
)

answered Mar 1, 2012 at 0:05

pifantastic

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Comments

sh03 · Accepted Answer · 2012-03-01 00:07:47Z

0

This should do the trick.

if (strlen($a) < 6) {
    $i = (6-strlen($a));
    $add = '';
    for ($x = 0; $x <= $i; $i++) {
        $add .= '0';
    }
    $a = $add.$a;
}

answered Mar 1, 2012 at 0:07

sh03

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