add months to a yyyymm dateformat

[cuboctahedron]

Hi,
I am trying to create a function that calculates new date (yyyymm) based on the number of months inserted.
e.g.
function(200409,13)//results in 200510
function (200409,1)//results in 200410

can anyone help please?

kind regards
Patrick

[AlsoGaiusCoffey]

Perhaps you should read up on the Date object in Flash, you know, their documentation is really good!

code:

---

var months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];

var d = new Date(2004, 10);

trace("Start date is "+months[d.getMonth()]+" in the year "+d.getFullYear());

d.setMonth(d.getMonth()+11);

trace("End date is "+months[d.getMonth()]+" in the year "+d.getFullYear());

---

(PS: getMonth returns a zero indexed month number so 0 is January, 1 is February and so on.)

[jbum]

Is that a polite way of saying RTFM ?

[cuboctahedron]

Hi have to following (working) function; perhaps not the most elegant, but workable though

function addmonths(startdatum, maanden)
{
jaardeel=startdatum.substring(0,4);
maanddeel=startdatum.substring(4,6);
maandtotaal=Number(maanddeel)+Number(maanden);
jaarverschil=Math.ceil(Number(maandtotaal)/12)-1;
jaardeel=Number(jaardeel)+Number(jaarverschil);
maanddeel=Number(maandtotaal)-(12*Number(jaarverschil));
maanddeel=String(maanddeel);
if (maanddeel.length==1){maanddeel="0"+maanddeel;}
jaardeel=String(jaardeel);
output=String(jaardeel)+String(maanddeel);

return output;
}

[jbum]

My version, using Coffey's example. I'm treating the YYYYMM string as a number, which simplifies things a bit.

code:

---

computeDateStr = function(dNum, monthOffset)

{

  dNum = Number(dNum); // insure it's a number so I can do some math on it

  yr = dNum / 100;

  mn = dNum % 100;

  dt = new Date(yr,mn-1);

dt.setMonth(dt.getMonth()+monthOffset);

	return dt.getFullYear()*100 + (dt.getMonth()+1);

}



trace(computeDateStr(200411,5));

---

[cuboctahedron]

Thanks!
jbum's version certainly rules over mine.

PS does it matter if I would use yr = Math.floor(dNum / 100); in your statement? It just seems more consistent leaving out decimals, incase they should occur.

[jbum]

Yes, you are right - you should use floor() or int() there - I forgot that actionscript doesn't do integer division.

Good call!

[websam]

Sorry J, just a bit minor modification:

computeDateStr = function(dNum, monthOffset)
{
        dNum = Number(dNum); // insure it's a number so I can do some math on it
        yr = Math.floor(dNum / 100);
        mn = dNum % 100;
        dt = new Date(yr,mn+monthOffset);
        return dt.getFullYear()*100 + dt.getMonth();
}

[AlsoGaiusCoffey]

I had to look at that for a while to see what you had done differently. All very elegant.

However, seeing as we are apparently trying to get this pedantically correct (and as JBum + websam have done all the hard work ) the return should probably be done as a string and yr, mn and dt should be declared using "var" so as to encapsulate them within the function and prevent any possible conflict with other values.