Equations calculator - help

Potices · 01-09-2013, 03:19 PM

Hey guys. I'm working on a program that can calculate your equations. I'm not finish yet but as you can see here, I want it to print out the 'c' variable and the 'b' variable via an alert. So what's wrong with it? Later I will make css and finish the code...

Code:

HTML:

<!DOCTYPE html>
<html>
    <head>
        <title></title>
        <link/>
        <script></script>
    </head>
    <body>
    <script type="text/javascript" src="script.js"></script>
    </body>
</html>

----------------------------------------------

Javascript:

Code:

var ligning = prompt("Indtast din ligning her:");

var calculator = function() {
    for(i = 0; j=true; i++) {
        var k = i;
        var a = ligning.substring(k,1+k);
        if (a === "=") {
            j = false;
            var b = ligning.substring(0, i);
            var c = ligning.substring(i+1, 200);
            alert("end.")
    }
        else {j=true;}
    }
};
alert(ligning);
alert(c);
alert(b);

WolfShade · 01-09-2013, 03:55 PM

You are closing the for loop before anything else is processed, so it will run indefinitely, as j will always be true.

Potices · 01-09-2013, 04:09 PM

Oh your right. I changed it, but It still doesn't work at all. I updated the thread, so the 'new' code is at the very top.

I did also add a new alert. In the event; 'if (a === "=")' I added the alert 'end' just so I could see if it could find the "=". But it couldn't, so my question is why, and how can I fix it?

007julien · 01-09-2013, 04:10 PM

A simpler variant :

Code:

var k=0;
while (ligning.substring(k) && ligning.substring(k,k+1)!=='=') k++;
   
   if (ligning.substring(k,k+1)==='=')  {// We find the sign = 
      var b = ligning.substring(0,k);
      var c = ligning.substring(k+1, 200);
   }
   else alert('This entry is not an equation');

But, an other sign = is possible in c !!!

Incidentally, there is no need to make a loop to find and cut a string on a sign =

Code:

var arrEqt = ligning.split('='); // give immediately arrEqt[0] and arrEqt[1] if the length of arrEqt is two !

Please use the Go Advanced and Code buttons...

Potices · 01-09-2013, 05:22 PM

Thank you very much 007julien! I'm new at Javascript and I will use the .split method instead. Thank you very much!