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The "Sum" Of Certain Array Values…

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Feb 23.2009

Hello.

Quick question…how do you add the value of certain slots in an array.

For instance with this code:

[CODE]
function convertToString(){

var first_example={};
first_example = readCookie(first_example);

var first_pics = first_example[“whatever1”].toString();
var second_pics = first_example[“whatever2”].toString();
var third_pics = first_example[“whatever3”].toString();
var fourth_pics = first_example[“whatever4”].toString();

var first_array = first_pics.split(“,”);
var second_array = second_pics.split(“,”);
var third_array = third_pics.split(“,”);
var fourth_array = fourth_pics.split(“,”);

alert[COLOR=”Blue”](eval(first_array[1] + first_array[0]))[/COLOR];

}
[/CODE]

..I’m trying to get the sum of the part highlighted in blue…and I know that what I have is wrong…so how would I
accomplish this feat..?..

to post a comment
JavaScript

6 Comments(s) ↴

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@JMRKERFeb 23.2009 — Not enough information from your example so this is just a guess ... ?

Assuming results of first_pics is a string something like: '1,2,3,4,5,6,7,8,9'

Check to make sure this is true with an alert(first_pics)

just after the assignment creation

Note, use of eval function is not the suggested way to do this.
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@ZeroKilledFeb 23.2009 — apologies, no useful information
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@ChuckBauthorFeb 23.2009 — 
Assuming results of first_pics is a string something like: '1,2,3,4,5,6,7,8,9'
[/QUOTE]

That's exactly right... now after I split by " , " I want to get the sum of first_pics[0] + first_pics[1]...and this is where the problem is...
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@ZeroKilledFeb 23.2009 — there is no need to use [b]eval[/b] method and it may make the code more harder to maintain. so, since each element of the array are string, you have to convert them to integer before sum them. you can use either [b]Number[/b] or [b]parseInt[/b] function:
alert(Number(first_array[1]) + parseInt(first_array[0]));
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@ChuckBauthorFeb 23.2009 — there is no need to use [b]eval[/b] method and it may make the code more harder to maintain. so, since each element of the array are string, you have to convert them to integer before sum them. you can use either [b]Number[/b] or [b]parseInt[/b] function:
alert(Number(first_array[1]) + parseInt(first_array[0]));[/QUOTE]

This is it...I almost wish I figured this out myself....I was close

instead I originally had [CODE]alert(Number(first_array[1]+first_array[0]));[/CODE]

...but thanks guys.
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@JMRKERFeb 23.2009 — Be careful here ...

alert(Number(first_array[1]+first_array[0]));

...vs...

alert(Number(first_array[1])+Number(first_array[0])))

... or ...

var S = Number(first_array[1])+Number(first_array[0]);

alert(S);


String concantonate here so you might evaluate "1'+'2' as '12' and not display the number you may wish as a sum of '3' instead.
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