15-11-2006, 03:53 PM
Just made this calculator for an assigment at uni, was just woundering if people could check it out, try and brake it. make it do unexpected things.
cheers
cheers
Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<title>Javascript Calculator</title>
<script language="JavaScript">
<!-- Begin
// if the number is 0, the new character will replace it, if it is not 0 then it will add it to the form.
function addChar(input, character) {
if(input.value == null || input.value == "0")
input.value = character
else
input.value += character
}
//Deletes the last digit in the form field.
function deleteChar(input) {
input.value = input.value.substring(0, input.value.length - 1)
}
//Changes the sign from - to + or + to -
function changeSign(input) {
if(input.value.substring(0, 1) == "-")
input.value = input.value.substring(1, input.value.length)
else
input.value = "-" + input.value
}
//Calculates the equation in the input field.
function compute(form) {
form.display.value = eval(form.display.value)
}
//Checks to see if the numbers/characters added into the input field are numbers or mathmatical symbals.
function checkNum(str) {
for (var i = 0; i < str.length; i++) {
var ch = str.substring(i, i+1)
if (ch < "0" || ch > "9") {
if (ch != "/" && ch != "*" && ch != "+" && ch !="-" && ch != ".") {
alert("Invalid Entry!")
return false
}
}
}
return true
}
// End -->
</script>
</head>
<body>
<form>
<input name="display" value="0" size=25>
<br />
<input type="button" value=" 7 " onClick="addChar(this.form.display, '7')">
<input type="button" value=" 8 " onClick="addChar(this.form.display, '8')">
<input type="button" value=" 9 " onClick="addChar(this.form.display, '9')">
<input type="button" value=" / " onClick="addChar(this.form.display, '/')">
<br />
<input type="button" value=" 4 " onClick="addChar(this.form.display, '4')">
<input type="button" value=" 5 " onClick="addChar(this.form.display, '5')">
<input type="button" value=" 6 " onClick="addChar(this.form.display, '6')">
<input type="button" value=" * " onClick="addChar(this.form.display, '*')">
<br />
<input type="button" value=" 1 " onClick="addChar(this.form.display, '1')">
<input type="button" value=" 2 " onClick="addChar(this.form.display, '2')">
<input type="button" value=" 3 " onClick="addChar(this.form.display, '3')">
<input type="button" value=" - " onClick="addChar(this.form.display, '-')">
<br />
<input type="button" value=" 0 " onClick="addChar(this.form.display, '0')">
<input type="button" value=" . " onClick="addChar(this.form.display, '.')">
<input type="button" value="+/-" onClick="changeSign(this.form.display)">
<input type="button" value=" + " onClick="addChar(this.form.display, '+')">
<br />
<br />
<input type="button" value="Clear" onClick="this.form.display.value = 0 ">
<input type="button" value="Delete" onClick="deleteChar(this.form.display)">
<input type="button" value="=" name="enter" onClick="if (checkNum(this.form.display.value))
{ compute(this.form) }">
</form>
</body>
</html>
