Press Button to display (the value in the button) on the Input Box.

**pbmods** · Aug 21 '07, 02:13 PM

Heya, Divina.

The problem you're having is that when you use parseInt(), you're no longer working with a reference to x's value; instead you're using a copy of it.

To make this work, you'll want to do something like this:
[code=javascript]
function calculation() {
value1=document .getElementById ("x").value; //input box
nine=parseInt(d ocument.getElem entById("nine") .value); // button

value1=nine;
}
[/code]

Note that since you never actually do anything with value1's value, there is no need to parseInt() it anyway.

You're looking for [code=javascript], by the way ~_^

**divina11** · Aug 21 '07, 02:35 PM

Acoder, I've tried the what you said and still it didn't work, Can you see my coding below, (thank you for your quick response):

[CODE=javascript]
<html>
<head>
<script>
function calculation() {
value1=document .getElementById ("x").value;
nine1=parseInt( document.getEle mentById("nine" ).value);

value1=nine1;
}
</script>

</head>
<body>

<input type="text" id="x" size="25"/>
<input type="button" id="nine" value="9" onclick="calcul ation()">

</body>
</html>[/CODE]

**pbmods** · Aug 21 '07, 02:42 PM

Heya, Divina.

Hm. Ok, try this:
[code=javascript]
function calculation() {
value1=document .getElementById ("x"); //input box
nine=parseInt(d ocument.getElem entById("nine") .value); // button

value1.value = nine;
}
[/code]

**divina11** · Aug 21 '07, 02:49 PM

Thank you Acoder that worked, thanks alot again.

**acoder** · Aug 21 '07, 03:16 PM

Originally posted by divina11

Thank you Acoder that worked, thanks alot again.

Glad you got it working, but I should point out it was pbmods that helped you!

**divina11** · Aug 21 '07, 03:44 PM

Final post of the day, In my Calculator Program I press the button 9, then I press button +, then I press 8, then I press button =, which will then display the result (17) in the text box.

Without using Objects, what is the best way to get this working. Please see code below:

[CODE=javascript]<html>
<head>
<script>

function digit8() {
value1=document .getElementById ("x");
Eight=parseInt( document.getEle mentById("eight ").value);

value1.value=Ei ght;
}

function digit9() {
value1=document .getElementById ("x");
Nine=parseInt(d ocument.getElem entById("nine") .value);

value1.value=Ni ne;
}

function equals() {
value1=document .getElementById ("x");
Nine=parseInt(d ocument.getElem entById("nine") .value);
Eight=parseInt( document.getEle mentById("eight ").value);
}

</script>

</head>
<body><br>

<input type="text" id="x" size="25"/>
<input type="button" id="eight" value=" 8 " onclick="digit8 ()">
<input type="button" id="add" value=" + " onclick="">
<input type="button" id="nine" value=" 9 " onclick="digit9 ()"><br><br>

<input type="button" id="equals" value=" = "onclick="" >

</body>
</html>[/CODE]

**pbmods** · Aug 21 '07, 03:44 PM

Originally posted by acoder

Glad you got it working, but I should point out it was pbmods that helped you!

lol It's the eyes.

**pbmods** · Aug 21 '07, 04:02 PM

Heya, Divina.

You'll need to build up an array of operands and values, then join() and eval() them.

First, you need to create a set of numerical buttons:
[code=html]
<input type="button" onclick="addToC alc(this.value) ;" value="1" />
etc.
[/code]

Then you need to set up your environment:
[code=javascript]
var calc = [];

function addToCalc(value )
{
/***************
*
* Pop the last value off of calc if possible.
* It makes it easier to process that way.
*/
var last = '';
if(calc.length > 0)
{
last = calc.pop();
}

switch(value)
{
/***************
*
* Operands terminate values.
*/
case '-':
case '*':
case '/':
case '+':
switch(last)
{
/***************
*
* Change operand if User pressed 'c' or hasn't entered a number yet.
*
* E.g., 1+ --> 1-
*/
case '-':
case '*':
case '/':
case '+':
calc.push(value );
break;

/***************
*
* Otherwise add the operand.
*
* E.g., 1+1 --> 1+1-
*/
default:
calc.push(last) ;
calc.push(value );
break;
}
break;

/***************
*
* The clear button removes the last item.
*
* E.g., 1+12345 --> 1+
* (or) 1+ --> 1
*/
case 'c':
break;

/***************
*
* Numbers get appended to the current item.
*
* E.g., 1+1 --> 1+12
* (or) 1+ --> 1+1
*/
default:
switch(last)
{
/***************
*
* If the last 'value' was an operand, put it back on and add the next value.
*/
case '-':
case '*':
case '/':
case '+':
calc.push(last) ;
calc.push(value );
break;

/***************
*
* Otherwise append the value to what's currently there.
*/
default:
calc.push(Strin g(last) + String(value));
break;
}
break;
}

// For debugging
alert(calc.join (' '));
}
[/code]

Then you can create a calculate button:
[code=html]
<input type="button" onclick="calcul ate();" value="=" />
[/code]

[code=javascript]
function calculate()
{
var result = eval(calc.join( ''));
delete calc;
calc = [];

// For debugging
alert(result);
}
[/code]

As this sounds suspiciously like a homework problem, I strongly advise you to ask me lots of questions so that you understand why this works. You (and your instructor!) will be a lot happier that way.

**divina11** · Aug 21 '07, 04:18 PM

I don't understant the comment: "Change operand if User pressed 'c' or hasn't entered a number yet".

Ta

**pbmods** · Aug 21 '07, 04:33 PM

Heya, Divina.

Originally posted by divina11

I don't understant the comment: "Change operand if User pressed 'c' or hasn't entered a number yet".

Think about how a physical calculator works. Suppose you were to press '1', then '+'. Then suppose you changed your mind and pressed '-'.

The way the calculator would handle that would be to replace the '+' with a '-' in the expression.

Similarly, the goal here is to replace the current operand with the new one.

For example, suppose your calc array looked like this:
[code=javascript]
calc = [
'12',
'+',
'15',
'*'
];
[/code]

If the User presses the '-' button, you want to change calc to this:
[code=javascript]
calc = [
'12',
'+',
'15',
'-' <--
];
[/code]

When addToCalc('-') runs, it pops off the last element in calc.
[code=javascript]
calc = [
'12',
'+',
'15'
];

last = '*';
[/code]

Then, we enter the switch statement, and we hit the case '-' (line 22).

So we switch(last) (line 26). Since it is an operand (case '*', line 35), we ignore the value of last and instead push the '-' onto calc (line 38):
[code=javascript]
calc = [
'12',
'+',
'15',
'-'
];

last = '*';
[/code]

Then we break, go to the alert statement, and you should see this:
12 + 15 -

**divina11** · Aug 21 '07, 04:53 PM

Sorry Sorry Sorry Pbmods for your hard work, I think it's a bit complex for me, I think there is an easier way but I've not sure how to implement it.

I was thinking user presses 8 + 9 =

Hence for each of these buttons I store it in a variable and then when user presses =, I do the sum when user presses =

Can you help me implement this?

Ta

**pbmods** · Aug 21 '07, 05:54 PM

Heya, Divina.

No problem. I had fun writing it anyway.

Sounds like what you'll want to do is create four textboxes:
[code=html]
<input id="number1" value="" />
<input id="operand" value="" />
<input id="number2" value="" />
<input id="answer" value="" />
[/code]

I presume you want the User to use number buttons instead of being able to type in the numbers; is this correct?

Similarly to what you were doing before, you'll want to store a reference to the text box that you want to edit:
[code=javascript]
/***************
*
* Initialize textbox as a global variable; we start with the first number.
*/
var current = document.getEle mentById('numbe r1');
[/code]

[code=html]
<input type="button" id="eight" value=" 8 " onclick="digit( 8);">
<input type="button" id="add" value=" + " onclick="digit( '+');">
<input type="button" id="nine" value=" 9 " onclick="digit( 9);"><br><br>
[/code]

To implement the digit() function:
[code=javascript]
function digit(value)
{
/***************
*
* Check to see if value is a number. If it is, append it to current.value.
*
* If it is an operand, set the value of the 'operand' textbox and then change current to reference the 'number2' textbox.
*/
}
[/code]

**divina11** · Aug 21 '07, 09:19 PM

y is a Global Variable to store operators (+,/,*,-), however i can't get the 'if' statement to work below:

[CODE=javascript]function equals() {
value1=document .getElementById ("v");

if (y=="+") { // I think the problem is here!!!!
alert("+ was selected");
var answer = (x+z);
value1.value=an swer;
}
else if (y=="*") { // I think the problem is here too!!!!
alert("* was selected");
}
}[/CODE]

**pbmods** · Aug 21 '07, 09:32 PM

Heya, Divina.

[CODE=javascript] works better than [CODE : javascript] ~_^

Try alert()ing y to see if it has a value.

Press Button to display (the value in the button) on the Input Box.

Press Button to display (the value in the button) on the Input Box.

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