Binary/Decimal Conversion



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BrettBits > Java and Javascript Programs > Binary/Decimal Conversion

To use this Javascript for your own, copy the contents of the textbox below, and paste them into Notepad. Then, save the contents as a .htm or .html file. The Javascript is now yours! Just ensure you give me proper credit for creating it.

Javascript Source Code

function convert() { //reads conversion type from drop-down box and performs appropriate operation

inputValue = ""; //input field's value
outputValue = ""; //output field's value
currnum = 1; //used in calculating output value

if(document.binaryform.conversionType.value == "b2d") { //if conversion is Binary To Decimal
	inputValue = document.binaryform.inputField.value; //read input value from input field

for (z=0; z <= inputValue.length-1; z++) { //ensure input contains only 1s and 0s
		if(inputValue.charAt(z) != "0" && inputValue.charAt(z) != "1") {
			alert("All digits must be a binary 0 or a 1."); //alert user of error
			return false; //abort conversion
		}
	}

outputValue = 0; //initially assume output value is zero

for(i = inputValue.length-1; i >= 0; i -= 1) { //for each binary digit in input
		//add base two value for each binary 1 in input
		outputValue += eval(inputValue.charAt(i)) * Math.pow(2, inputValue.length-i-1);
	}

document.binaryform.outputField.value = outputValue; //display output value in output field

} else if(document.binaryform.conversionType.value == "d2b") { // if conversion is Decimal to Binary
	inputValue = eval(document.binaryform.inputField.value); //read input value from input field

currNum = 1;

//currnum is to equal the smallest base 2 number smaller than the input value
	while(currnum*2 <= inputValue) {
		currnum = currnum * 2;
	}
	
	while (currnum > 0.5) { //this loop reduces currnum by two until less than one remains
		if(inputValue >= currnum) {
			outputValue += "1"; //add 1 to binary output
			inputValue -= currnum;
		} else if(inputValue < currnum) {
			outputValue += "0"; //add 0 to binary output
		}
		currnum /= 2;
	}
	document.binaryform.outputField.value = outputValue; //display output value in output field
}
}
// -->
</script>

<tr>
<td colspan="2" align="center">
Conversion Type: 
<select name="conversionType">
<option value="b2d">Binary to Decimal</option>
<option value="d2b">Decimal to Binary</option>
</select>
</td>
</tr>

<tr>
<td align="center">
<b>Input</b><br />
  <input type="text" name="inputField" size="40" />  
</td>
<td align="center">
<b>Output</b><br />
  <input type="text" name="outputField" size="40" />  
</td>
</tr>

</table>
</form>
</center>

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