TInterpreter::Execute and parameters passed by reference

ROOT
1

Hello,

I wonder whether/how TInterpreter::Execute can cope with functions that have parameters passed by reference. Such as

How could I obtain, via TInterpreter::Execute, x any y coordinates of let’s say the first point of TGraph?

Thanks a lot, Kašpi.

2

Hi,

You can use something likeTString::Format("%d, *(int*)0x%x, *(int*)0x%x",i,&x,&y);

Cheers,
Philippe.

3

Thank you very much for your help. I tried that, but I was not successful. Could you please look at the following code?

#include "TGraph.h"
#include "TString.h"
#include "TInterpreter.h"

int main()
{
	TGraph *g = new TGraph();
	g->SetPoint(0, 1, 2);
	double x = -1, y = -1;

	int error = 0;

	int i = 0;
	gInterpreter->Execute(g, g->IsA(), "GetPoint", (const char *) TString::Format("%d, *(int*)0x%x, *(int*)0x%x", i, &x, &y), &error);

	printf("error = %i, x = %f, y = %f\n", error, x, y);
}

The program prints error = 0, x = -1.000000, y = -1.000000
No error is signalized but this may be the same issue as in my other post.

Would you know where the problem is?

Thanks again, Kašpi.

4

Hi,

The call has to be tweaked a bit:gInterpreter->Execute(g, g->IsA(), "GetPoint", TString::Format("%d, *(double*)0x%lx, *(double*)0x%lx", i, &x, &y), &error)

Cheers,
Philippe.