Problem with vector<double> alocation

[Ivan Paganini]

Hello all.
I'm trying to use a vector<double> to alocate de data that i need, and
I am passing by reference to the function to receive the values. The
code goes like this:
//code


void GenerateRandomP ositions(vector <double>& posiX, vector<double>&
posiY, int nbneurons, int* sizespace)
{posiX.clear();
posiY.clear();

for(i=0;i<NbNeu rons;i++)
{
posiX.push_back ((double)(rand( )%sizespace[0]+1));
posiY.push_back ((double)(rand( )%sizespace[1]+1));
}
}

//end code

where i need the values of posiX and posiY returned to the program.
The size of NbNeurons is about 10, and sizespace is a number that the
program gets from the number of coordinates in my database. When i try
to run the program, i get the segmentation fault. What can be the
problem?

Thanks.

Ivan S>P<M
Grupo de Visão Cibernética - IFSC - USP - Br

[Victor Bazarov]

Re: Problem with vector&lt;doubl e&gt; alocation

"Ivan Paganini" <ivanpaganini@y ahoo.com.br> wrote...[color=blue]
> Hello all.
> I'm trying to use a vector<double> to alocate de data that i need, and
> I am passing by reference to the function to receive the values. The
> code goes like this:
> //code
>
>
> void GenerateRandomP ositions(vector <double>& posiX, vector<double>&
> posiY, int nbneurons, int* sizespace)
> {posiX.clear();
> posiY.clear();
>
> for(i=0;i<NbNeu rons;i++)
> {
> posiX.push_back ((double)(rand( )%sizespace[0]+1));
> posiY.push_back ((double)(rand( )%sizespace[1]+1));
> }
> }
>
> //end code
>
> where i need the values of posiX and posiY returned to the program.
> The size of NbNeurons is about 10, and sizespace is a number that the
> program gets from the number of coordinates in my database. When i try
> to run the program, i get the segmentation fault. What can be the
> problem?[/color]

The problem is most likely in 'sizespace'. Since you don't show
how you call your 'GenerateRandom Positions' function, there is no
way to tell what specifically is going on.

BTW, using '%' with the result of calling 'rand' is not a good idea.
See comp.lang.c FAQ for the explanation why and what to use instead.

Victor

[Rob Williscroft]

Re: Problem with vector&lt;doubl e&gt; alocation

Ivan Paganini wrote in news:ac0d0790.0 310040650.3107c 228
@posting.google .com:
[color=blue]
> Hello all.
> I'm trying to use a vector<double> to alocate de data that i need, and
> I am passing by reference to the function to receive the values. The
> code goes like this:
> //code
>
>[/color]

#include <iostream>
#include <ostream>
#include <vector>
#include <iterator>
#include <algorithm>

using std::vector;

void GenerateRandomP ositions(
vector<double>& posiX, vector<double>& posiY,
int nbneurons, int* sizespace
)
{
posiX.clear();
posiY.clear();

for( int i=0; i<nbneurons; i++)
{
posiX.push_back ((double)(rand( )%sizespace[0]+1));
posiY.push_back ((double)(rand( )%sizespace[1]+1));
}
}


int main()
{

int ss[2] = { 100, 200 };
vector< double > px, py;

GenerateRandomP ositions( px, py, 10, ss );

std::copy(
px.begin(), px.end(),
std::ostream_it erator< double >( std::cout, "," )
);
std::cout << "\n";

std::copy(
py.begin(), py.end(),
std::ostream_it erator< double >( std::cout, "," )
);
std::cout << std::endl;
}

[color=blue]
>
> where i need the values of posiX and posiY returned to the program.
> The size of NbNeurons is about 10, and sizespace is a number that the
> program gets from the number of coordinates in my database. When i try
> to run the program, i get the segmentation fault. What can be the
> problem?
>[/color]

After fixing 1 error (spelling) and adding main() the above
compiles and runs.

HTH

Rob.
--

http://www.victim-prime.dsl.pipex.com/

[Kevin Goodsell]

Re: Problem with vector&lt;doubl e&gt; alocation

Ivan Paganini wrote:
[color=blue]
> Hello all.
> I'm trying to use a vector<double> to alocate de data that i need, and
> I am passing by reference to the function to receive the values. The
> code goes like this:
> //code
>
>
> void GenerateRandomP ositions(vector <double>& posiX, vector<double>&
> posiY, int nbneurons, int* sizespace)
> {posiX.clear();
> posiY.clear();
>
> for(i=0;i<NbNeu rons;i++)
> {
> posiX.push_back ((double)(rand( )%sizespace[0]+1));
> posiY.push_back ((double)(rand( )%sizespace[1]+1));
> }
> }
>
> //end code
>[/color]

http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.8

Pay particular attention to items 1 through 3.

-Kevin
--
My email address is valid, but changes periodically.
To contact me please use the address from a recent posting.