I have an array with arrays of two elements. Now I would like to sort all values ending at zero (e.g. arr[3][0], arr[1][0]) to be sorted from low to high.
Then I would like to have the values ending at 1 (e.g. arr[2][1], arr[1][1]) to also be sorted, but not on its own order, but in the same order as the first array.
Here is what I tried:
int compareInts(const void* a, const void* b)
{
return ( *(int*) a[0] - *(int*) b[0] );
}
int arr[4][2];
arr[0][0] = 50;
arr[0][1] = 0;
arr[1][0] = 40;
arr[1][1] = 1;
arr[2][0] = 50;
arr[2][1] = 2;
arr[3][0] = 85;
arr[3][1] = 3;
qsort( arr, 4, sizeof(int), compareInts );
I would like to have the following result:
arr[0][0] = 40;
arr[0][1] = 1;
arr[1][0] = 50;
arr[1][1] = 0;
arr[2][0] = 50;
arr[2][1] = 2;
arr[3][0] = 85;
arr[3][1] = 3;
Just implement your own search algorithm (use bubble sort or whatever you think might be most efficient) and do the comparison/swapping similar to the following pseudo code:
if(a[i][0] > a[j][0])
{
t[0] = a[i][0];
t[1] = a[i][1];
a[i][0] = a[j][0];
a[i][1] = a[j][1];
a[j][0] = t[0];
a[j][1] = t[1];
}
If you'd like to sort based on multiple collumns you'd just have to repeat this comparing other sub array elements and sorting the least significant column first.
Edit:
I thik this should also be possible using qsort(). You just have to set the element size accordingly (should be 2 * sizeof(int) in your example). Leave the rest of your code unchanged (although I'm not sure about this and can't test run it right now).