Code-Bin #223 - Binary Conversion Functions

Binary Conversion Functions
Posted by: TRUSTAbyss | February 12, 2009 @ 2:01pm

PHP Code

<?php
/**
 * Binary Conversion Functions
 * Created by: Joshua H. (TRUSTAbyss)
 *
 * These two functions allow you to convert
 * decimal numbers to binary, or binary strings
 * to decimal. An example on the proper use of
 * these functions is shown below.
 *
 * [Example Usage]
 * Decimal to Binary: dec2bin(173)
 * Binary to Decimal: bin2dec('1101')
 *
 * NOTE: PHP already includes built-in functions
 * for binary conversions. I wrote these so you're
 * not stuck with PHP's functions.
 *
 * Provided by: http://www.trustabyss.com/
 */

function dec2bin($decimal = 0)
{
	$binString = '';
	$base_table = array();
	$bit_number = 0;
	$i = 0;
	
	while ($bit_number <= $decimal)
	{	
		$bit_number = pow(2, $i);
		$base_table[] = $bit_number;
		$i++;
	}
	
	$last_index = count($base_table) - 1;

unset($base_table[$last_index]);
	rsort($base_table);
	
	foreach ($base_table as $bitPosition)
	{
		if ($decimal >= $bitPosition)
		{
			$decimal -= $bitPosition;
			$binString .= '1'; 
		}
		else
		{
			$binString .= '0';
		}
	}
	
	if (strlen($binString) < 8)
	{
		$zero_padding = '';
		
		for ($i = 0; $i < (8 - strlen($binString)); $i++)
		{
			$zero_padding .= '0';
		}
		
		$binString = $zero_padding.$binString;
	}
	
	return $binString;
}

function bin2dec($binString = '00000000')
{	
	$decimal = 0;
	$bin_array = str_split($binString, 1);
	$base_table = array();

for ($i = count($bin_array) - 1; $i >= 0; $i--)
	{
		$base_table[] = pow(2, $i);
	}
	
	for ($i = 0; $i < count($bin_array); $i++)
	{
		if ($bin_array[$i] == '1')
		{
			$decimal += $base_table[$i];
		}
	}
	
	return $decimal;
}
?>

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Author Comments

These two functions allow you to convert decimal to binary, or binary to decimal.

[Example Usage]

Decimal to Binary: dec2bin(173)
Binary to Decimal: bin2dec('1101')

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82 Votes