How do I make an array of numbers that I can add or multiply to get a numerical answer?

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Hello JS Coders,

First I searched the Internet for a solution to adding two array numbers. Nothing made sense.
I am having a hard time understanding how to create an array of numbers that I can do simple math operations on.
var cnum = [4, 5, 2, 7];

If I add cnum[0] and cnum[2] I hope to get 6, but I get 42 ?.

I actually believe I am the worlds worst programmer, and am humble enough to admit it.

JavaScript

   var cnum = [4, 5, 2, 7];
   d = cnum[0] + cnum[2];
   alert("add two array numbers = " d);  // 42 ?

It seems like JS is treating the cnum's as strings.
How can I create arrays that I can preform math on?

Thanks,
Jim

Posted 17-Aug-14 11:04am

JimOr

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[no name] 17-Aug-14 18:45pm

You would need to use parseInt on the array elements to make them numbers.

JimOr 17-Aug-14 20:46pm

Wes, OK, I will try the parseInt.

I also put in the missing comma, the Alert text appeared but no result value.

How would I apply parseInt?

Thank You Kindly,
Jim

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Peter Leow · Accepted Answer · 2014-08-17T13:31:00

Solution 1

You code is fine except one missing comma in alert.

C#

var cnum = [4, 5, 2, 7];
d = cnum[0] + cnum[2];
alert("add two array numbers = " +d);

Posted 17-Aug-14 13:31pm

Peter Leow

Comments

JimOr 17-Aug-14 21:35pm

Still having problems with adding two numbers from an array:
Now I have:
var cnum = [4, 5, 2, 7];
alert(parseInt(cnum[1]));
d = parseInt(cnum[0]) + parseInt(cnum[2]);
var cs = d.toString();
alert("add two array numbers = ", cs); //
The above code still does not work. Any ideas?

Peter Leow 17-Aug-14 21:42pm

Why don't you copy and paste my code to a html page and test it?

JimOr 17-Aug-14 22:51pm

Thank You Peter.
Kindly,
Jim

JimOr 17-Aug-14 22:27pm

To: Peter Leow, Yes your suggestion DOES seem to work. (6)

So I continue to explore other suggestions:
Some now working, some not...
var cnum = [4, 5, 2, 7];
alert(parseInt(cnum[3],10) + parseInt(cnum[1],10)); // 12, 7 + 5 = 12, OK this one works
d = (parseInt(cnum[0],10) + parseInt(cnum[2],10)).toString(); // does not work, 4+2 = 6
alert("add two array numbers = ", d); // the two numbers added does not appear.