Thread: qsort() won't work properly..

Hi
i am facing some problem with qsort() function it work well if the last element of array is larger then the 2nd last element. But in case if last element of array is smaller then the 2nd last it will sort the whole array and remains the last as it is. For example

Code:

int group_id_local[max_j]={2,1,4,5};// it work fine, output should be {1,2,4,5} 
//but if i have this one 
int group_id_local[max_j]={2,1,4,3};// output should be {1,2,4,3}
/* COMPARE FUNCTION FOR USING QSORT()*/
int cmpfunc (const void* a, const void* b)
{
if (*(int *)a < *(int *)b) return -1;
if (*(int *)a > *(int *)b) return 1;
return 0;
}

qsort(group_id_local,max_j, sizeof(int), cmpfunc);
int j;
printf ("sorted Array:\n");
for (j=0; j<=max_j; j++){
printf ("%d\n ",group_id_local[j]);
}

Plz help me why it will not sort the last element?

Code:

for (j=0; j<=max_j; j++){

Code:

printf ("%d\n ",group_id_local[j]);
}

Code:

here max_j=3

and we have 4 elements thats why i use j<=max_j.
It is not overrun. This thing make me crazy. I spend alot of time to figure out whats going on but still the same issue.

Originally Posted by Salem

> for (j=0; j<=max_j; j++)
Perhaps it's because you have an array overrun in your printing.

So whatever you think is the last element is actually garbage.

I get my problem where i am calling qsort()

Code:

qsort(group_id_local,max_j, sizeof(int), cmpfunc);
// I was passing the wrong count, my count should be max_j+1 
qsort(group_id_local,max_j+1, sizeof(int), cmpfunc)

Thanks

Originally Posted by gevni

Code:

int group_id_local[max_j]={2,1,4,5};// it work fine, output should be {1,2,4,5} 
//but if i have this one 
int group_id_local[max_j]={2,1,4,3};// output should be {1,2,4,3}

Originally Posted by gevni

Code:

for (j=0; j<=max_j; j++)
{
     printf ("%d\n ",group_id_local[j]);
}

here max_j=3

and we have 4 elements thats why i use j<=max_j.

Originally Posted by gevni

Code:

qsort(group_id_local,max_j, sizeof(int), cmpfunc);
// I was passing the wrong count, my count should be max_j+1 
qsort(group_id_local,max_j+1, sizeof(int), cmpfunc)

Something is wrong. If "max_j" really is 3 then you should get a warning when you initialize your array and you would still have a buffer overrun. Or do you decrease "max_j" after initializing (which would be rather strange)?

Bye, Andreas