steinbring/DecimalToBinary.htm

## DecimalToBinary.htm
<!--
Joe Steinbring
http://steinbring.net
11/10/2013
-->
<html>
<head>
	<title>Decimal to Binary Converter</title>
</head>
<body>
<h1>Convert between decimal and binary</h1>
<p>This is meant to convert unsigned base 2 numbers to base 10 and back again.  The maximum number this app can handle is 2^64/2.  Hopefully you don't need to worry about anything larger than that.  This is written in JavaScript.  Feel free to copy it. </p>

<form method="post">
	<p>
	<label for="numDecimal">Decimal</label>
	<input name="numDecimal" type="text" size="25">
	</p>
	<p>
	<label for="numBinary">Binary</label>
	<input name="numBinary" type="text" size="25">
	</p>
	<p>
	<button name="buttDecimalToBinary" type="button" onclick="this.form.numBinary.value = DecimalToBinary(this.form.numDecimal.value);">
		Decimal To Binary
	</button>
	<button name="buttBinaryToDecimal" type="button" onclick="this.form.numDecimal.value = BinaryToDecimal(this.form.numBinary.value);">
		Binary To Decimal
	</button>
	</p>
</form>

<script type="text/javascript">
	function DecimalToBinary(DecimalValue){
		var BinaryValue = '';
		// Loop from 2^64/2 to 1
		for (var i=64; i>=1; i--){
			// Is 2^i/2 within DecimalValue?
			if(DecimalValue >= Math.pow(2,i)/2){
				// If so, add a 1 to BinaryValue and subtract 2^i/2 from DecimalValue
				BinaryValue = BinaryValue+'1';
				DecimalValue = DecimalValue - (Math.pow(2,i)/2);
			}
			else if(BinaryValue.indexOf("1") != -1){
				// If not, add a 0, but only if there is already a 1 in the value
				BinaryValue = BinaryValue+'0';
			}
		}
		return BinaryValue;
	}
	function BinaryToDecimal(BinaryValue){
		var DecimalValue = 0;
		// Flip the character array (aka string) in order to make itterating over it easier
		BinaryValue = BinaryValue.split("").reverse().join("");
		// Loop over BinaryValue (from left to right)
		for (var i=BinaryValue.length-1;i>=0;i--){
			// Is there a 1 in the place?
			if(BinaryValue[i] == '1'){
				// If so, add 2^i/2 to DecimalValue
				DecimalValue = DecimalValue + (Math.pow(2,i+1)/2);
			}
		}
		return DecimalValue;
	}
</script>
</body>
</html>
	<!--
	Joe Steinbring
	http://steinbring.net
	11/10/2013
	-->
	<html>
	<head>
	<title>Decimal to Binary Converter</title>
	</head>
	<body>
	<h1>Convert between decimal and binary</h1>
	<p>This is meant to convert unsigned base 2 numbers to base 10 and back again. The maximum number this app can handle is 2^64/2. Hopefully you don't need to worry about anything larger than that. This is written in JavaScript. Feel free to copy it. </p>

	<form method="post">
	<p>
	<label for="numDecimal">Decimal</label>
	<input name="numDecimal" type="text" size="25">
	</p>
	<p>
	<label for="numBinary">Binary</label>
	<input name="numBinary" type="text" size="25">
	</p>
	<p>
	<button name="buttDecimalToBinary" type="button" onclick="this.form.numBinary.value = DecimalToBinary(this.form.numDecimal.value);">
	Decimal To Binary
	</button>
	<button name="buttBinaryToDecimal" type="button" onclick="this.form.numDecimal.value = BinaryToDecimal(this.form.numBinary.value);">
	Binary To Decimal
	</button>
	</p>
	</form>

	<script type="text/javascript">
	function DecimalToBinary(DecimalValue){
	var BinaryValue = '';
	// Loop from 2^64/2 to 1
	for (var i=64; i>=1; i--){
	// Is 2^i/2 within DecimalValue?
	if(DecimalValue >= Math.pow(2,i)/2){
	// If so, add a 1 to BinaryValue and subtract 2^i/2 from DecimalValue
	BinaryValue = BinaryValue+'1';
	DecimalValue = DecimalValue - (Math.pow(2,i)/2);
	}
	else if(BinaryValue.indexOf("1") != -1){
	// If not, add a 0, but only if there is already a 1 in the value
	BinaryValue = BinaryValue+'0';
	}
	}
	return BinaryValue;
	}
	function BinaryToDecimal(BinaryValue){
	var DecimalValue = 0;
	// Flip the character array (aka string) in order to make itterating over it easier
	BinaryValue = BinaryValue.split("").reverse().join("");
	// Loop over BinaryValue (from left to right)
	for (var i=BinaryValue.length-1;i>=0;i--){
	// Is there a 1 in the place?
	if(BinaryValue[i] == '1'){
	// If so, add 2^i/2 to DecimalValue
	DecimalValue = DecimalValue + (Math.pow(2,i+1)/2);
	}
	}
	return DecimalValue;
	}
	</script>
	</body>
	</html>