[SOURCE]

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#define MAX 100

static int Compare(const void *element_1, const void *element_2)
{
  int i = *(int *)element_1,
      j = *(int *)element_2;
	 	
  if ( i > j ) return (-1);

  if ( i < j ) return (1);
  
  return (0);
}

main()
{
  int scores[MAX], input, i, j, k, n, count[5];
  int sum, high, low, varsum;
  float average, var;
  
  puts("TEST STATISTICS:\n");
  for(;;)
  {
	  puts("\nEnter the test scores (-9 after the last score entered)");
	  i = 0;
	  do
	  {
		  if (i > MAX - 1)
		  {
			  puts("Array is full!\n");
			  break;
		  }
		  printf("Score #%i -> ", i+1);
		  scanf("%d", &input);
		  while(getchar() != '\n');
		  if(input != -9) scores = input;
			
		  if((input < 0 || input > 101) && (input != -9))
		  {
			  puts("Error: Data Must Be In Range of 0 to 100");
			  --i;
		  }
		  else if(input/ 101 != 0)
		  {
			  puts("Error: Data Must Be In Range And Not Decimal");
			  --i;
		  }
		  if(input == -9 && i == 0) break;
		  ++i;
	  }
	  while(input != -9);
	  
	  if(i > 0)
	  {
		  if(i< MAX -1) i = i - 2;
		  else  --i;
		  for(j = 0; j <= 4; ++j) count[j] = 0;
		  sum = 0;
		  high = scores[0];
		  low = scores[0];
		  for(j = 0; j <= i; ++j)
		  {
			  sum = sum + scores[j];
			  if(scores[j] < low) low = scores[j];
			  if(scores[j] > high) high = scores[j];
			  if(scores[j] > 89) ++count[0];
			  else if(scores[j] > 79) ++count[1];
			  else if(scores[j] > 69) ++count[2];
			  else if(scores[j] > 59) ++count[3];
			  else ++count[4];
		  }
		  average = (float)sum/(i+1);
		  varsum = 0;
		  for(j = 0; j <= i; ++j)
			  varsum = varsum + (scores[j] - average) * (scores[j] - average);
		  var = varsum/i;
		  printf("   Average ---- %5.2f\n"
		    	 "   High ------- %3i\n"
				 "   Low  ------- %3i\n"
				 "   Variance --- %5.2f\n"
				 "   Std. Dev --- %5.2f\n"
				 "   Distribution:\n"
				 "        (90 - 100) --- %3i\n"
				 "        (80 -  89) --- %3i\n"
				 "        (70 -  79) --- %3i\n"
				 "        (60 -  69) --- %3i\n"
				 "        ( 0 -  59) --- %3i\n"
				 "\n\n   Bar Graph\n\n"
				 "        (90 - 100) ",     
				 average, high, low, var, sqrt(var),
				 count[0], count[1], count[2],
				 count[3], count[4]);
		  for(k = 1; k <= count[0]; ++k) putchar('*');
		  fputs("\n        (80 -  89) ", stdout);
		  for(k = 1; k <= count[1]; ++k) putchar('*');	  
		  fputs("\n        (70 -  79) ", stdout);
		  for(k = 1; k <= count[2]; ++k) putchar('*');
		  fputs("\n        (60 -  69) ", stdout);
		  for(k = 1; k <= count[3]; ++k) putchar('*');
		  fputs("\n        ( 0 -  59) ", stdout);
		  for(k = 1; k <= count[4]; ++k) putchar('*');
		/*  puts("\n   Scores in Descending Sequence:\n");
		  n = sizeof(scores) / sizeof (int);
		  qsort(scores, n, sizeof(int), Compare);
		  for(k = 0; k <= i; ++k) 
                    printf("         %2i   %3i\n", k + 1, scores[k]); */
		  //PROBLEM AREA!
		  printf("\n   Total Number of Tests -> %i", i+1); 
	  }
	  else break;
  }
  return(0);
}

[/SOURCE]