Segmentation fault

[trxrse]

Hello,

I've got the following piece of code:

#include <string>
#include <fstream>
#include <cstdlib>
#include <vector>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>

vector <vector <double data;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data.push_back( vector <double>());
for (long j=0;j<Count_Gri d_Northing-1;j++){
data[i][j]=0;
}
}

vector <vector <double data_occupied;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data_occupied.p ush_back(vector <double>());
for (long j=0;j<Count_Gri d_Northing-1;j++){
data_occupied[i][j]=0;
}
}

Every time I run it I get "Segmentati on Fault". What am I doing
wrong, here, people???


Thanks
trxrse

[Andre Kostur]

Re: Segmentation fault

"trxrse" <Remus.SEPP@t-mobile.co.ukwro te in
news:1170264252 .011112.10030@j 27g2000cwj.goog legroups.com:

Hello,
>
I've got the following piece of code:
>
#include <string>
#include <fstream>
#include <cstdlib>
#include <vector>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>
>
vector <vector <double data;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data.push_back( vector <double>());
for (long j=0;j<Count_Gri d_Northing-1;j++){
data[i][j]=0;

data[i][j] is referring to an element in the vector that you just pushed
onto data. That vector is still empty, thus you've accessed beyond the
end of the container. You probably want to replace your loop over j
with:

data[i].resize(Count_G rid_Northing);

}
}
>
vector <vector <double data_occupied;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data_occupied.p ush_back(vector <double>());
for (long j=0;j<Count_Gri d_Northing-1;j++){
data_occupied[i][j]=0;

Same as above.

}
}
>
Every time I run it I get "Segmentati on Fault". What am I doing
wrong, here, people???

Accessing beyond the end of a container. Undefined Behaviour, which
happens to be manifesting as a segfault.

[Rolf Magnus]

Re: Segmentation fault

trxrse wrote:

Hello,
>
I've got the following piece of code:
>
#include <string>
#include <fstream>
#include <cstdlib>
#include <vector>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>
>
vector <vector <double data;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data.push_back( vector <double>());

Simpler and quite a bit more efficient than repeated push_back() in the loop
would be a:

data.resize(Cou nt_Grid_Easting-1);

before the loop.

for (long j=0;j<Count_Gri d_Northing-1;j++){
data[i][j]=0;

Here is your problem. The inner vectors are all empty, i.e. have a size of
0. In the outer loop, you did it right by using push_back(). Why not in the
inner loop? The last line should be:

data[i].push_back(0);

Or again replace the for loop with a:

data[i].resize(Count_G rid_Northing-1);

which will also default-initialize all the elements.


In total, you can replace the whole thing with:

vector <vector <double data(Count_Grid _Easting-1,
vector<double>( Count_Grid_Nort hing-1));

[=?ISO-8859-1?Q?Erik_Wikstr=F6m?=]

Re: Segmentation fault

On 2007-01-31 18:24, trxrse wrote:

Hello,
>
I've got the following piece of code:
>
#include <string>
#include <fstream>
#include <cstdlib>
#include <vector>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>
>
vector <vector <double data;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data.push_back( vector <double>());

Adds an empty vector to data.

for (long j=0;j<Count_Gri d_Northing-1;j++){
data[i][j]=0;

Tries to access the j'th element in the empty vector.

If you want to add a vector of size Count_Grid_East ing - 1 with all
elements 0 you should use
data.push_back( vector<double>( Count_Grid_East ing - 1, 0));
instead.

--
Erik Wikström

[Jerry Coffin]

Re: Segmentation fault

In article <1170264252.011 112.10030@j27g2 000cwj.googlegr oups.com>,
Remus.SEPP@t-mobile.co.uk says...

[ ... ]

vector <vector <double data;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data.push_back( vector <double>());
for (long j=0;j<Count_Gri d_Northing-1;j++){
data[i][j]=0;
}
}

Perhaps something like this would work a bit better:

vector<doublete mp(Count_Grid_N orthing-1);
vector<vector<d oubledata(Count _Grid_Easting-1, temp);

By default, the elements of temp will be default constructed, which
means zero-filled in the case of arithmetic types. data is then
constructed with each element a copy of temp, so we end up with a vector
of vectors, all filled with zeros. The one shortcoming is that we're
creating an extra vector (temp) just to initialize data. If that's a
major problem, you could do something like this:

vector<vector<d ouble data(Count_Grid _Easting-1);

for (size_t i=0; i<data.size(); i++)
data[i].resize(Count_G rid_Northing);

--
Later,
Jerry.

The universe is a figment of its own imagination.

[trxrse]

Re: Segmentation fault

Thanks very much - you're really kind people. Indeed, this was the
problem.

Thanks
trxrse


On 1 Feb, 06:32, Jerry Coffin <jcof...@taeus. comwrote:

In article <1170264252.011 112.10...@j27g2 000cwj.googlegr oups.com>,
Remus.S...@t-mobile.co.uk says...
>
[ ... ]
>

vector <vector <double data;
for (long i=0;i<Count_Gri d_Easting-1;i++){
data.push_back( vector <double>());
for (long j=0;j<Count_Gri d_Northing-1;j++){
data[i][j]=0;
}
}

>
Perhaps something like this would work a bit better:
>
vector<doublete mp(Count_Grid_N orthing-1);
vector<vector<d oubledata(Count _Grid_Easting-1, temp);
>
By default, the elements of temp will be default constructed, which
means zero-filled in the case of arithmetic types. data is then
constructed with each element a copy of temp, so we end up with a vector
of vectors, all filled with zeros. The one shortcoming is that we're
creating an extra vector (temp) just to initialize data. If that's a
major problem, you could do something like this:
>
vector<vector<d ouble data(Count_Grid _Easting-1);
>
for (size_t i=0; i<data.size(); i++)
data[i].resize(Count_G rid_Northing);
>
--
Later,
Jerry.
>
The universe is a figment of its own imagination.

[Default User]

Re: Segmentation fault - TPA

trxrse wrote:

Thanks very much - you're really kind people. Indeed, this was the
problem.

Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or the group FAQ list:
<http://www.parashift.c om/c++-faq-lite/how-to-post.html>

[Old Wolf]

Re: Segmentation fault - TPA

On Feb 2, 7:33 am, "Default User" <defaultuse...@ yahoo.comwrote:

trxrse wrote:

Thanks very much - you're really kind people. Indeed, this was the
problem.

>
Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or the group FAQ list:
<http://www.parashift.c om/c++-faq-lite/how-to-post.html>

Top-posting was correct in this case. The OP's comments
did not refer to any specific piece of the message he
was replying to, and did not require any context to
interpret.

[Kai-Uwe Bux]

Re: Segmentation fault - TPA

Old Wolf wrote:

On Feb 2, 7:33 am, "Default User" <defaultuse...@ yahoo.comwrote:

>trxrse wrote:

Thanks very much - you're really kind people. Indeed, this was the
problem.

>>
>Please don't top-post. Your replies belong following or interspersed
>with properly trimmed quotes. See the majority of other posts in the
>newsgroup, or the group FAQ list:
><http://www.parashift.c om/c++-faq-lite/how-to-post.html>

>
Top-posting was correct in this case. The OP's comments
did not refer to any specific piece of the message he
was replying to, and did not require any context to
interpret.

Actually, the way I read it, the "this" in "Indeed, this was the problem"
refers to a specific piece of information, and the quoting style of the OP
turns the pronoun into a dangling reference.


Best

Kai-Uwe Bux

[Old Wolf]

Re: Segmentation fault - TPA

On Feb 5, 11:47 am, Kai-Uwe Bux <jkherci...@gmx .netwrote:

Old Wolf wrote:

On Feb 2, 7:33 am, "Default User" <defaultuse...@ yahoo.comwrote:

trxrse wrote:
Thanks very much - you're really kind people. Indeed, this was the
problem.

>

Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or the group FAQ list:
<http://www.parashift.c om/c++-faq-lite/how-to-post.html>

>

Top-posting was correct in this case. The OP's comments
did not refer to any specific piece of the message he
was replying to, and did not require any context to
interpret.

>
Actually, the way I read it, the "this" in "Indeed, this was the problem"
refers to a specific piece of information, and the quoting style of the OP
turns the pronoun into a dangling reference.

Nevertheless, it is clear that the message is a thankyou
note, and 'this' refers to the problem that the OP had
and is now solved. It's not necessary to know what the
actual problem was, in order to understand the purpose
and content of the post.

[Default User]

Re: Segmentation fault - TPA

Old Wolf wrote:

On Feb 2, 7:33 am, "Default User" <defaultuse...@ yahoo.comwrote:

trxrse wrote:

Thanks very much - you're really kind people. Indeed, this was the
problem.

Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or the group FAQ list:
<http://www.parashift.c om/c++-faq-lite/how-to-post.html>

>
Top-posting was correct in this case.

Impossible, as top-posting is never correct. If the quotes weren't
relevant to the reply, then they didn't belong at all. And of course,
you're wrong because the person was replying directly to something in
the quotes, i.e. the solution to the problem.

I try to put "- TPA" in the header when I post this message. If it
bothers you, consider filtering it.




Brian