How to convert Month Variable into date

Hi Guys,

I have requirement where user will input the month thru Bex variable ( on 0calmonth) .

There are 5 columns in report.

4 of them has got the 0calmonth in each row and need to be selected as per the 0calmonth input.

5th column need to be derived based on below logic :

BUDAT LE to last day of previous month (from input month ), with AUGDT =Blank or AUGDT > last day of previous month

I need to copy the value of the variable through Customer Exit into new variable and planning to write this in CMOD enhancment.

This variable will contain the Last day of previous month.

I will then use this variable to restrict the data set for last column.

Can somebody help me with the code .

Thanks.