hi guyz..

i am new to program in the unix environment. I was coding a prog to implement merge sort algo here a fragment (as i feel might have caused the error) goes..

Code:

void msort(int *array,int start,int end)
{
if start=end then return back;
if end-start=1 implies there are only two elements swap if necessary n return;
msort(array,start,(start+end)/2);
msort(array,(start+end)/2,end);
/* at this point we have two sorted arrays one frm start to(start+end)/2 rest the other*/
/*create a dummy array of required size merge the two sorted arrays by comparing cunterpart elements n swapping if necessary n store in this dummy array*/
/*now make array point to dummy*/
array = dummy;
/*at every recursive step dummy is newly created that fits the whole size of the array (i.e frm start to end) n so this shud not create a memory conflict as dummy is local to each function*/
/* when everything is done array is sorted*/
}

i have written this code n running this gave me the error "glibc detected Aborted n there were some address variables i suppose

so as a primary step to debug i tried tracing the path at every new recursive step n so i printed the start and end values immediately after declarations n the final sorted array at the end of each recursive step n .

even then i found everything worked well n the steps were printed in order as the ought to be until this "glibc" was encountered

i feel that i amn't very precise till this step n so i post my code , so still if u are unable to figure out plz copy n paste this code n compile it so that u may get an idea where the real error goes..

here is the code...

Code:

#include"stdio.h"
#include"malloc.h"
#include"stdlib.h"
void msort(int *,int,int);
main()
{
int *arr,n,i;
int start,end;
printf("Input n (no. of elements in the array) : "); //n is size of array
scanf("%d",&n);
arr = (int *)malloc(4*n);
for(i=0;i<n;i++)
scanf("%d",arr+i);
msort(arr,0,n-1); //passing the entire arry with start=0 end=n-1
}
void msort(int *p,int start,int end)
{
int temp,i,mid=(start+end)/2,j;
int *q=(int *)malloc(4*((end-start)+1)),*dummy;
printf("Entered msort with start=%d end=%d\n",start,end);
if(!q)
{
printf("failure allocating memory\n");
exit(0);
}
if(end-start == 1 && start<end) //array has only two elements
{
if(p[start] > p[end])
{
temp = p[start];
p[start] = p[end];
p[end] = temp;
}
return;
}
else if(start == end) // array has a single element
return;
msort(p,start,(start+end)/2);
msort(p,(start+end)/2+1,end);
j=start;
if(mid+1 == end) //mid is (start+end)/2 n array has three elements
{
if(p[start+1] < p[end])
{
q[j++] = p[start];
q[j++] = p[start+1];
q[j++] = p[end];
}
else
{
if(p[start] < p[end])
{
q[j++] = p[start];
q[j++] = p[end];
q[j++] = p[start+1];
}
else
{
q[j++] = p[end];
q[j++] = p[start];
q[j++] = p[start+1];
}
}
}
else
{
for(i=start,j=start ; i<mid ; i++)
{
if(p[i] > p[i+mid])
{
temp = p[i];
p[i] = p[i+mid];
p[i+mid] = temp;
}
q[j++] = p[i];
q[j++] = p[i+mid];
}
}
dummy=p; //this is not the dummy array as i talked of earlier its rather q
p=q;
free(dummy);
printf("Now array is : ");
for(i=start;i<=end;i++)
printf("%d ",p[i]);
puts("");
}

hope now u got my problem

plzz help me n thnx in advance....