10 replies to this topic

[John]

Here is a simple piece of code I whipped up to do my homework for me. It converts a binary number to its decimal equivalent. However unlike the bindec function, this will preserve the binary/radix point (not to mention it will output the work too).

<?php

/**
 * Convert a binary number with our without
 * a radix point to its decimal equivalent.
 *
 * @param $binary The binary number to convert.
 * @param $output Show the calculations.
 * @return The decimal conversion
 */
function bin2dec($binary, $output = false) {
	$N = 0;
	$o = "";
	list ( $rhs, $lhs ) = explode ( ".", $binary );
	$rhs = strrev ( $rhs );
	for($i = 0; $i < strlen ( $rhs ); $i ++) {
		$d = $rhs [$i] * pow ( 2, $i );
		$N = $d + $N;
		$o = ($d == 0) ? $o : $o . $d . " + ";
	}
	
	for($i = 0; $i < strlen ( $lhs ); $i ++) {
		$d = $lhs [$i] * pow ( 2, - ($i + 1) );
		$N = $d + $N;
		$o = ($d == 0) ? $o : $o . $d . " + ";
	}
	
	return ($output) ? substr ( $o, 0, - 3 ) . " = " . $N : $N;
}

?>

Usage:

echo bin2dec ( "1011101.1000101", true );

Output:

1 + 4 + 8 + 16 + 64 + 0.5 + 0.03125 + 0.0078125 = 93.5390625

[morefood2001]

If only I had this last semester, my life would have been so much easier. Thanks for writing this because it will help me when I get to writing MIPS code next week :)

[TkTech]

hehe ~ why didn't you use it

[John]

Jordan said:

What would this output?

echo bin2dec ( "1011101.1000101 01011101 10111011", true );  

That would output an incorrect number. Try it yourself and see :P

Jordan said:

Why did you not use the PHP Standard Funcion: PHP: bindec - Manual

As stated in my post (and I am assuming this), PHP won't consider 1011101.1000101 a valid binary string due to the radix point, plus (again stated in my original post) bindec doesn't show me the "work"

[TkTech]

My total bad. Any particular reason you wrote it in PHP? Much easier and faster to do this in ASM - not to mention the multitude of examples already out there to do exactly this.

[Xav]

Lol Jordan.

[John]

TkTech said:

My total bad. Any particular reason you wrote it in PHP? Much easier and faster to do this in ASM - not to mention the multitude of examples already out there to do exactly this.

primarily because I don't know asm.

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[morefood2001]

Jordan said:

I know why you are writing it and I know your reasons. You harassed me with those questions when I wrote the Ascii calculator so I figured I'd get you back.

Go Jordan! I should have wrote this a long time ago, but I didn't feel like it and it wouldn't have helped me on the test :P At least John took the time to write it :)