How to modify values within an array sequentially

Question

I'm trying to sort an array so that the values are ordered from largest to smallest.

Then I want to modify the values so that no two values are equal, by subtracting 1 from the higher index value and adding 1 to the lower index value.

I've managed to order the values how I want, but I'm stuck on how to modify the array values so that no two are equal. How should I proceed with this problem?

#include <stdio.h>
#include <stdlib.h>

/*declare variables*/
int s, t, c, l, e;
int RawVals[5];

/*this sorts an input array from largest to smallest*/
int cmpfunc (const void *a, const void *b)
{
  return (*(int *) b - *(int *) a);
}

/* DiePyramid Generator */
int main ()
{
/*Value inputs are taken here*/
  printf ("Enter Skill Level, "), scanf ("%d", &s);
  printf ("Enter Applied Tags, "), scanf ("%d", &t);
  printf ("Enter characteristic Value, "), scanf ("%d", &c);
  printf ("Enter Enhanced Tags, "), scanf ("%d", &e);
  printf ("Enter Legendary Tags, "), scanf ("%d", &l);

/*These inputs are then put into the RawVals array*/
  RawVals[0] = s;
  RawVals[1] = t;
  RawVals[2] = c;
  RawVals[3] = e;
  RawVals[4] = l;

/*Print RawVals before sorting*/
  printf("\n");
  printf("Entered Array: ");
  for (int i=0;i<5;i++){
    printf("%d ", RawVals[i]);
  }

/*This function then takes the RawVals array, and sorts it using cmpfunc*/
  qsort (RawVals, 5, sizeof (int), cmpfunc);

/*Add in some spacing between array outputs*/
  printf("\n");
  printf("\n");

/*This prints out the values in the RawVals array after sorting*/
  printf(" Sorted Array: ");
  for (int i=0; i<5; i++){
      printf ("%d ", RawVals[i]);
    }

/*Pyramid Forming Function*/    
  for (int i=0;i<5;i++){
    int j = 0;
    int k = 1;
    for (int p=0;p<5;p++){
      if (RawVals[j] >= RawVals[k]){
        if (RawVals[j] > 0){
          RawVals[j]++;
          RawVals[k]--;
        }
      }
    j++;
    k++;
    }
  }

/*Print out the modified values that now form the pyramid*/
  printf("\n");
  printf("\n");
  printf(" Modded Array: ");
    for (int i=0; i<5; i++){
        printf ("%d ", RawVals[i]);
      }
}

Using the above,

an input of 1 2 2 4 5 should give me 5 4 3 2 0

the actual output is 10 4 -3 7 -4

In the section /*Pyramid Forming Function*/ variable int k = 1 can index out of range on the last i loop iteration, and access RawVals[5]. So you have undefined behaviour. — Weather Vane
– Weather Vane, Commented Jan 17, 2019 at 23:50

Craig Estey · Accepted Answer · 2019-01-18 00:03:26Z

1

As Weather Vane pointed out, k is going one beyond the end.

Also, your outer if condition is incorrect. It should be == and not >=

Here's the corrected code.

Note the change in the for loop for p to prevent k from going too high (i.e. it should do only 4 iterations and not 5)

/*Pyramid Forming Function*/
for (int i = 0; i < 5; i++) {
    int j = 0;
    int k = 1;

    for (int p = 1; p < 5; p++) {
        if (RawVals[j] == RawVals[k]) {
            if (RawVals[j] > 0) {
                RawVals[j]++;
                RawVals[k]--;
            }
        }
        j++;
        k++;
    }
}

answered Jan 18, 2019 at 0:03

Craig Estey

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