Thread: HELP me with my Qsort Program

Code:

#include <stdio.h>
#define maxsize 10

void quicksort (int a, int b);
//void mergesort ();

float ES26[11];
int i, j, k, x=1, mean, median, mode;
float *ptr, sum;

int main ()
{
    printf("Input at most 10 floating point numbers, each entry followed by ENTER. \nInput 0 if you want to stop:\n");
    for (i=1, j=1; j==1 || i==10; i++)
    {  
        printf("%d) ", i);
        scanf("%f", &ES26[i]);
        ptr=&ES26[i];
        
        if (*ptr==0)
        {
            x=i-1;
            j=2;
        }
        if (i==10)
        {
            x=i;
            j=2;
        }
    }
    
    if (x==2 || x==4 || x==6 || x==8 || x==10)
    {
    printf("\nYou entered %i valid entries.", x);
    ptr = &ES26[i];
    quicksort(0, x-1);
    
    printf("\nSupposed to Quicksort.");
    }

    if (x==1 || x==3 || x==5 || x==7 || x==9)
    {
    printf("\nYou entered %i valid entries.", x);
    //meregesort
    
    printf("\nSupposed to Mergesort.");
    }
    
    //ptr = &ES26[i];
    
    for (i=1; i<=x; i++) //for printing
    {
        ptr=&ES26[i];
        printf("\nEntry %i is %f", i, *ptr);
        sum = sum + *ptr;
    }
        printf("\nThe mean is %f", sum/x);
    
    getchar();
    getchar();
    getchar();
    getchar();
}


void quicksort(int a, int b)
{
  ptr=&ES26[a];
  //*ptr=ES26[a];
  int rtidx=0, ltidx=0, k=a, l=0;
  float leftarr[maxsize], rtarr[maxsize];
  //float pivot = ES26[a];
  
  if (a==b) return;
  while (k<b)
  {
    ++k;
    
	 if(ptr[k] < ptr[a])
	 {
	  leftarr[ltidx] = ptr[k];
	  ltidx++;
	  }
	  
		else
		{
		rtarr[rtidx] = ptr[k];
		rtidx++;
        }
  }
 
	 k=a; //reset k to a
	 
	 *ptr=ES26[a];
	 for(l=0; l<ltidx; ++l)
	 
     ptr[k++] = leftarr[l];
	 ptr[k++] = *ptr;
	 
	 for(l=0; l<rtidx; ++l)
     ptr[k++] = rtarr[l];
	 
	 if(ltidx>0)
     quicksort(a, a+ltidx-1);
	 
     if(rtidx>0)
     quicksort(b-rtidx+1, b);
	 }

here is an example of what I get if i run my program:

Input at most 10 floating point numbers, each entry followed by ENTER.
Input 0 if you want to stop:
1> 11.23
2> 43.553
3> 196.4673
4> 0.8874
5> 23.67
6> 90.5
7> 0

You entered 6 valid entries.
Supposed to Quicksort.
Entry 1 is 11.230000
Entry 2 is 11.230000
Entry 3 is 23.670000
Entry 4 is 11.230000
Entry 5 is 196.467300
Entry 6 is 90.500000

Can somebody help me point out where the mistake is? Thanks a lot!