The merger sorting of C# sorting algorithm

//Group sort (target array, start position of subtable, end position of subtable)  private static void MergeSortFunction(int[] array, int first, int last)
  {
   try
   {
    if (first < last) //The length of the subtable is greater than 1, then the following recursive processing will be entered.    {
     int mid = (first + last) / 2; //The location of sub-table division     MergeSortFunction(array, first, mid); //Recursively divide the divided left subtable     MergeSortFunction(array, mid + 1, last); //Recursively divide the divided right subtable     MergeSortCore(array, first, mid, last); // Orderly integrate left and right sub-tables (the core part of merge sorting)    }
   }
   catch (Exception ex)
   { }
  }
 
  //The core part of merge sorting: merge two ordered left and right subtables (differentiated by mid) into an ordered table  private static void MergeSortCore(int[] array, int first, int mid, int last)
  {
   try
   {
    int indexA = first; //The starting position of the sub-table on the left    int indexB = mid + 1; //The starting position of the sub-table on the right    int[] temp = new int[last + 1]; //Declare an array (stagely store all ordered sequences of left and right subtables): the length is equal to the sum of the lengths of left and right subtables.    int tempIndex = 0;
    while (indexA <= mid && indexB <= last) //Do traverse left and right sub-tables. If one of the sub-tables has been traversed, the loop will jump out    {
     if (array[indexA] &lt;= array[indexB]) //The number of the left subtable at this time <= the number of the right subtable at this time     {
      temp[tempIndex++] = array[indexA++]; //Put the number of the left subtable into the temporary array and traverse the subtable of the left subtable++     }
     else//Number of the left subtable at this time >Number of the right subtable at this time     {
      temp[tempIndex++] = array[indexB++]; //Put the number of the right subtable into the temporary array and traverse the subtable of the right subtable++     }
    }
    //After one side sub-table is traversed, the loop jumps out and the remaining numbers on the other side sub-table are placed in the temporary array at one time (ordered)    while (indexA &lt;= mid)
    {
     temp[tempIndex++] = array[indexA++];
    }
    while (indexB &lt;= last)
    {
     temp[tempIndex++] = array[indexB++];
    }
 
    //Write the ordered sequence in the temporary array to the target array setting position to make the merged array segments orderly    tempIndex = 0;
    for (int i = first; i &lt;= last; i++)
    {
     array[i] = temp[tempIndex++];
    }
   }
   catch (Exception ex)
   { }
  }