Check if a date range is within a date range

Question

I have the following class:

public class Membership
{
    public DateTime StartDate { get; set; }
    public DateTime? EndDate { get; set; } // If null then          


        

Answer 1

public bool DoesAnOfferAlreadyExistWithinTheTimeframeProvided(int RetailerId, DateTime ValidFrom, DateTime ValidTo)
        {
            bool result = true;

            try
            {
                // Obtain the current list of coupons associated to the retailer.
                List retailerCoupons = PayPalInStore.Data.RetailerCoupon.Find(x => x.RetailerId == RetailerId).ToList();

                // Loop through each coupon and see if the timeframe provided in the NEW coupon doesnt fall between any EZISTING coupon.
                if (retailerCoupons != null)
                {
                    foreach (RetailerCoupon coupon in retailerCoupons)
                    {
                        DateTime retailerCouponValidFrom = coupon.DateValidFrom;
                        DateTime retailerCouponValidTo = coupon.DateExpires;

                        if ((ValidFrom <= retailerCouponValidFrom && ValidTo <= retailerCouponValidFrom) || (ValidFrom >= retailerCouponValidTo && ValidTo >= retailerCouponValidTo))
                        {
                            return false;
                        }
                    }
                }

                return result;
            }
        catch (Exception ex)
        {
            this.errorManager.LogError("DoesAnOfferAlreadyExistWithinTheTimeframeProvided failed", ex);
            return result;
        }
    }