Two Dimensional array sort 1

[rgarro]

How do you sort a 2 dimensional array???

 

[BoulderBum]

I haven't tested this yet, and I don't know if it works, but the following should give you a starting point. Pointer arithmatic (sometimes) works with 2 dimensional arrays, and I think using pointers for a traversal of the array is a bit simpler than the alternative (given the needed comparisons in the following algorithm). For clarity's sake, I've used a simple bubble sort. You can certainly find a more efficient algorithm if you're worried about performance.

int array[ size1 ][ size2 ] = ...;

int *temp,
*ptr;

for (j = 0; j < size1 * size2 - 1; j++ )
for (i = 0, ptr = &array[ 0 ][ 0 ]; //reset ptr & i
i < size1 * size2 - 1; i++ )
{
if ( *(temp = ptr) > *(++ptr) )
swap( temp, ptr ); //user defined function
}

 

[rgarro]

Thank you very much for your time...it is much appreciated.

 

[BoulderBum]

No prob.

I got to wondering about it, and I think assigning a pointer to another pointer may produce an error (cause the other pointer may get dragged along for the ride if the first pointer changes). I forget. I'm still pretty new at this.

Anyways, my new idea is this:

int temp,
*ptr;

for (j = 0; j < size1 * size2 - 1; j++ )
for (i = 0, ptr = &array[ 0 ][ 0 ]; //reset ptr & i
i < size1 * size2 - 1; i++ )
{
if ( (temp = *ptr) > *(++ptr) ) // i.e. ( n > n + 1 )
swap( temp, *ptr ); //user defined function
}

I really should sit down and try to compile some of this for my own interest. Did either of these work?