date format change in C#

function MakedateFormat(format) {
           if (format != null) {
               if (format.search("/") || format.search("-") || format.search(" ")) {
                   var array = format.split(new String("/", "-", " "), 10);
                   var month = array[1];
                   switch (month) {
                       case "Jan":
                           array[1] = "01";
                           break;
                       case "Feb":
                           array[1] = "02";
                           break;
                       case "Mar":
                           array[1] = "03";
                           break;
                       case "Apr":
                           array[1] = "04";
                           break;
                       case "May":
                           array[1] = "05";
                           break;
                       case "Jun":
                           array[1] = "06";
                           break;
                       case "Jul":
                           array[1] = "07";
                           break;
                       case "Aug":
                           array[1] = "08";
                           break;
                       case "Sep":
                           array[1] = "09";
                           break;
                       case "Oct":
                           array[1] = "10";
                           break;
                       case "Nov":
                           array[1] = "11";
                           break;
                       case "Dec":
                           array[1] = "12";
                           break;
                   }
                   var realyear = array[2];
                   array[2] = parseInt(realyear); //+ parseInt(2000));
                   format = array[0] + "/" + array[1] + "/" + array[2];
                   return format;
               }
           }
           return format;
       }

DateTime thisDate = new DateTime(2011, 6, 10);
thisDate.ToString("d"-"MMMM"-"yyyy")