Vector Class Discussion

I created a structure "state" that has inside some Vec4i variables and a list containing states

std::list<state> stateInfo;

when i add the first data to stateInfo I got a crash if I use gcc 4.8.1 with optimization enabled ( setting no optimization solve the problem)

state s;

s.vector=0; //<-- Vec4i

stateInfo.push_back(s); <-- CRASH

if I replace the Vec4i with an int the problem is gone.
have you some idea of how to solve the problem? have you ever had such a problem?

best regards Marco

I would never use the standard template library (STL) on speed-critical applications (see my C++ manual). If you can set a reasonable maximum size for your list at compile time then just use a simple array. This is the fastest solution. If you need an array with dynamic size then you may use AlignedArray from www.agner.org/optimize/cppexamples.zip

I would like to add something to the question of Mr Belli, about problems with vectorclass and STL container.

This is my example :

#include "vectorclass.h"
#include <iostream>
#include <vector>

class myClass
{
private:
double g[4];
Vec4d av;
public:
myClass();
void prt();
};

myClass::myClass()
{
double f[4]={1,2,3,4};
av.load(f);
std::cout<<av.extract(0)<<std::endl; //THIS CALL IN THE CONSTRUCTOR DOESN'T CAUSE ANY PROBLEM
}

void myClass::prt()
{
std::cout<<av.extract(0)<<std::endl; //THE SAME CALL HERE CAUSES THE PROGRAM TO CRASH
}

int main()
{
std::vector<myClass> aset;
aset.push_back(myClass());
aset.push_back(myClass());
aset[0].prt(); //CALL prt() AND... CRASH!
return(0);
}

this code, compiled with GCC on windows crashes as member function prt() is called. Note that :

1. the same call inside the constructor does not cause the crash..why??
2. if the member double g[4] is removed from myClass, the problem disappears;
3. if the std::vector has just one entry the problem disappears,
4. the same code compiled with GCC in Linux works without crashing

... As I'm not a professional programmer I cannot understand what is happening, I hope someone of you can have some idea about it.

Finally, let me say thank you Mr Agner for such a good piece of code!

Renato

So don't ever put vector classes into STL or other containers.