typedef struct{}*poly;

typedef struct{}*poly;

type568

Member #8,381

March 2007

I have gotten a problem, I want to swap structs, fast. (swap their places..)

1typedef float vect0r[4]; 
2 
3typedef struct
4  {
5  vect0r cor[3];
6  float z;
7  int col;
8  }flat; 
9 
10flat *cube;
11 
12void some_function()
13  {
14  cube=(flat*)malloc(sizeof(flat)*poly);
15 
16 
17  for(i=0;i<poly;i++)
18    for(j=i;j<poly;j++)
19      if(cube<i>.z<cube[j].z)
20        {
21        cube<i>+=cube[j];
22        cube[j]=cube<i>-cube[j];
23        cube<i>-=cube[j];
24        }
25  }

The sorting, of course returns an error... i tried various combinations of *, and & and again, of course none helped me.

Would you do please.. ?

X-G

Member #856

December 2000

... why would + and - work on a struct without those operators defined? Hell, what do you even expect it to do in the first place?

Copy them as usual. Use a temporary copy if you'd like.

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kazzmir

Member #1,786

December 2001

First of all it looks like you are trying to sort these things so use qsort. Then don't make an array of structs, make an array of pointers to structs.

1flat **cube;
2 
3int compare_flat( void * a, void * b ){
4   flat * a1 = (flat *) a;
5   flat * b1 = (flat *) b;
6   if ( a1->z < b1->z ){
7      return -1;
8   } else if ( a1->z > b1->z ){
9      return 1;
10   } else {
11      return 0;
12   }
13}
14 
15int main(){
16   cube = (flat **) malloc( sizeof(flat*) * 15 );
17   for ( int i = 0; i < 15; i++ ){
18         cube[ i ] = (flat *) malloc( sizeof(flat) );
19         ...init..
20   }
21 
22   qsort( cube, sizeof(flat*), 15, compare_flat );

Matt Smith

Member #783

November 2000

Quote:

Then don't make an array of structs, make an array of pointers to structs.

No harm in using qsort on an array of structs, if the structs aren't enormous.

type568

Member #8,381

March 2007

Structs are small, but might be a huge amount...

Thanks kazzmir.

I expected to swap pointers.. While there are no pointers

EDIT: here how I made it though:

1 
int i,j;
int* array=(int*)malloc(sizeof(int)*poly);
4 
for(i=0;i<poly;i++)
  array<i>=i;
7 
for(i=0;i<poly;i++)
  for(j=i;j<poly;j++)
    if(cube[array<i>].z<cube[array[j]].z)
      {
      array<i>+=array[j];
      array[j]=array<i>-array[j];
      array<i>-=array[j];
      }
16 
for(i=0;i<poly;i++)
  triangle(dest,cube[array<i>].cor[0][0],cube[array<i>].cor[0][1],cube[array<i>].cor[1][0],cube[array<i>].cor[1][1],cube[array<i>].cor[2][0],cube[array<i>].cor[2][1],cube[array<i>].col);

BAF

Member #2,981

December 2002

That is horrible. It's much easier, and better looking, if you just swap the elements the proper way, instead of using that extra array.

BAF.zone | SantaHack!

type568

Member #8,381

March 2007

I dunno how much slower is it.. And probably the best way is **poly.. But it would be faster than swapping contents of the struct for sure.