payroll period start date and end date

Hi all,

this is naresh.

i am giving payroll period as input and i want to display that start date and end date in display mode at selection-screen itself.

so, i have done it but i have hard coded the values based upon the months.

i.e if month = '01' then start-date is 01/01/2014 and end date as 31/01/2014 based upon payroll period.

i was asked to get start-date and end-date using Function Modules, i should give input as payroll period and dates should get.

can any1 tell which Function Module is used to get start date and end date?

thanks,

naresh.