Advanced C Programming
                                           Spring 2004


   Excercise 9E (Extra exercise; qsort)
         
        Qsort function is in standard C function library. Qsort can be 
        used to sort all kinds of arrays using different kinds of 
        sorting criterias. That is the reason why qsort is implemented
        as a generic function. It means, that the user of qsort can 
        decide what is the sorting criteria. The user writes his/her own 
        comparison function to describe how two elements of the array are
        compared during the sorting process. This comparison function is
        then passed as a parameter to the qsort function. Qsort functions
        then calls this comparison function when it has to decide whether
        to swap the elements of the array or not. It is agreed that
        comparison function shoud return -1 if	the first parameter is 
        less than the second, 0 if they are equal and 1 if the first 
        parameter is greater than the second. 

	The basic idea how qsort can be used to sort the array of persons 
	according their names or ages was presented in the class. 
        To demonstrate the versatility of qsort function for youself 
        write a program that sorts an array of arrays. Now we want that 
        qsort sorts the rows of an two dimensional array so that the row
        that has smallest sum of elements is as the first row. 

 
	Remark. You do'nt have to bother yourself with reading the
        information to the array in the beginning from the keyboard. 
        Instead you can initialize your array in the source code in 
	the following way (this is adequate test to show whether your
        program works or not)
		
	               int array[4][3] = { {3, 3, 5},
                                           {2, 2, 5},
                                           {2, 1, 5},
                                           {2, 3, 5}
                       };

	
	In this case your programs output should be as follows:
	
	Original array:

		3   3   5
                2   2   5
                2   1   5
                2   3   5		
       
        Sorted array

                2   1   5
                2   2   5
                2   3   5
                3   3   5
                


         Remark. Remember that we now sort the the rows in order. The rows are
         moved as a whole. In the data above the roes are moved in the following 
         way:
	         Original row no    New row no    Sum of elements at the new row
		        0               3	      8
                        1               1             9
                        2               0             10
                        3               2             11