casting to string in vex?

[Aearon]

is there anyway to cast an integer to string in vex?

i'm trying to do an equivalent of the partition sop in vex using something like:

string grpname = "grp" + (string) ptnum;

addgroup(grpname,ptnum)

(this is just a simple example that would create a group per point named grp$PT in expression speak)

is this possible? casting to string like that doesn't seem to work.

Edited November 6, 2008 by Aearon

[rdg]

is there anyway to cast an integer to string in vex?

take a look at the sprintf function:

string mystring = sprintf("grp%d", pnum);

it should do what you want.

Looking forward to see what you're up to ...

[eetu]

grpname = sprintf("grp%d", ptnum); i think.

edit: ach, rdg was quicker

Edited November 6, 2008 by eetu

[Aearon]

ah yeah great, much better

thanks guys

[Aearon]

hm... weird stuff happening now.

i have this code:

printf("grp%d\n",ptnum);
addgroup(sprintf("grp%d", ptnum),ptnum);

the printf generates the expected output (grp0,grp1,...,grp1042)

i have 1043 points so everything seems correct

but the groups created look like this:

256 points in grp0
256 points in grp256
256 points in grp768
19 points in grp1024

[eetu]

Interesting. My bet is this is caused by the parallel SIMD nature of how vex is executed.

How do you get "ptnum"?

eetu.

[Aearon]

hm possible. maybe it executes blocks of 256 points at a time? interesting!

ptnum is just the global var. the two lines are all the code there is.

[Mario Marengo]

hm possible. maybe it executes blocks of 256 points at a time? interesting!

ptnum is just the global var. the two lines are all the code there is.

Looks like the optimizer thinks some part of your code is not worthy of inclusion

Anyway, this hack seems to work (tried it in an InLine VOP inside a VopSop):

if(!ptnum) {
   int i;
   for(i=0;i<Npt;i++) {
	  addgroup(sprintf("grp%d",i),i);
   }
}

[rdg]

why:

if(!ptnum) {

Is ptnum set later to execute it just once?

[Mario Marengo]

why:

if(!ptnum) {

Is ptnum set later to execute it just once?

Not sure I understand the question. My thought behind it was that even if a bunch of threads (or "virtual processors" in SIMD) were spawned, one per point, that conditional would still only be true for just one of them. And ptnum is only referenced that one time (the local variable "i" takes over after that).

[rdg]

oh.

I missed ptnum being a global variable ...