Add months and set the last day of the month in one step

[C# Programming]

I want to add months and set the day as last day of that added month. I know i can do in the following way,

DateTime ldtManipulatedDate = new DateTime(1998,lintMonths,1).AddMonths(lintAddMonths);
ldtManipulatedDate = new DateTime(ldtManipulatedDate.Year ,ldtManipulatedDate.Months,DateTime.DaysInMonth(
ldtManipulatedDate.Year,ldtManipulatedDate.Months));


The above code will first add months and then set the day as last day of that added month.
But i want this in one step as i am instantiating two times.

Please let me know how can i do it?