Re: Converting a physical string to a integer

[putha]

Hi all,

I am having a problem converting a physical string to a integer. I have a dropdown list of a few items but are numbers though in chracters. I ned to output the value and the text of the selected item. As I cannot use a if-else statement, any help would be great.

<select id="std_num" onchange="displayValue()">
            	<option value="Two">Two</option>
                <option value="Zero">Zero</option>
                <option value="Five">Five</option>
                <option value="Three">Three</option>
                <option value="Two">Two</option>
                <option value="Zero">Zero</option>
             </select>

function displayValue()
{
	alert(document.getElementById('std_num').value);
	var c = (document.getElementById('std_num').value);
}

[Kor]

1. Why don't you write straight the numbers as values?
2. Otherwise, use a loop:

<select id="std_num" onchange="displayValue(this.value)">

function displayValue(v){
var num=['Zero','One','Two','Three','Four','Five','Six','Seven','Eight','Nine','Ten'], c, n, i=0;
while(n=num[i++]){
v==n?c=i-1:null;
}
alert(c);
}

As I cannot use a if-else statement

Why not? It is required, there is no other way, as the CPU does not know the English language

[putha]

Hey Kor,

Your function works can you somewhat elaborate on how it is converting the written string to its perspective numerical value.

Thanks for your help

[Kor]

Hey Kor,

Your function works can you somewhat elaborate on how it is converting the written string to its perspective numerical value.

Thanks for your help

It is not a conversion, it is an univoque correspondence between an element in an array and his index in that array. In JavaScript the counting index of the array elements starts from 0, thus I use this fortuitous chance to make the human logical correspondence. "Zero" is the first element, thus it has the index 0, "One" is the second, thus it has the index 1

Zero => 0
One =>1

and so on.

[Logic Ali]

You could also use an object as a lookup table:

<select id="std_num" onchange="alert( wordToDigit( this.value ) )">
  <option value="">Select</option>
  <option value="Two">Two</option>
  <option value="Zero">Zero</option>
  <option value="Five">Five</option>
  <option value="Three">Three</option>
  <option value="Four">Four</option>
  <option value="Seven">Seven</option>
</select>

<script type='text/javascript'>

function wordToDigit( v )
{ 
 return { 'Zero':0,'One':1,'Two':2,'Three':3,'Four':4,'Five':5,'Six':6,'Seven':7,'Eight':8,'Nine':9 }[ v ];
}

</script>