see content of a vector in debugging

[taram]

hi,

I use c::b (svn 5616)  and in my c::b project I have defined a typdef like this:

typedef vector<string> vstr;

And use it like following:

--------------------------
vstr v;

v.push_back("bla bla");
---------------------------

Everything works fine.

But when I debug, I can not see in the  "Local variabel"  an "understandable" content of the string vector.

When I open the "local watches" I only see "_M_start"  and "_M_finish" etc. with a hex number.




The only thing which is working when I watch a concrete cell of the vector is:


Add watch -->v[0]


then I can see the string of the first element of the string vector.

Is there a way to see all strings of the string vector in the debugger? That would be great.

The "v[0]" (element view) works fine but it would be very convenient to see all strings in the string vector "en block".


Thanks for your help

Martin

[ollydbg]

I test your code, found it is even bad in my system(MinGW, WindowsXP), I can't view "v[0]".
See my screenshot


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[Jenna]

If v[0] works for you, you can try to watch v as array (add it to watch window, edit it and check watch as array).

[Jenna]

I test your code, found it is even bad in my system(MinGW, WindowsXP), I can't view "v[0]".
See my screenshot

You have to use the []-operator in your program, otherwise it gets not compiled in and therefore cannot be used by gdb.

@taram:
watching the variable as array does not work here.

[ollydbg]

Thanks Jens for your hints.

Here is a workaround.

Code Select Expand


#include <iostream>
#include <string>
#include <vector>

using namespace std;

typedef vector<string> vstr;

int main()
{
    vstr v;
    v.push_back("bla bla");
    string v0 = v[0];
    cout << "Hello world!" << endl;
    return 0;
}

I can only watch "v0" (see the screen shot)




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[taram]

Hi,

first of all, thank all for your help and replies to my question. Sorry for my delayed answer, but I am here in Calgary and -8h behind European time

However, here the code which I was using for testing:

Code Select Expand


#include <iostream>
#include <string>
#include <vector>

using namespace std;

typedef vector<string> vstr;

int main()
{
   vstr v;
   v.push_back("1. bla bla");
   v.push_back("2. bla bla");
   v.push_back("3. bla bla");

   int a[3] ={11, 22, 33};



   for (unsigned int f = 0; f<3; f++)
   {
       cout <<" a[" << f <<"] = " << a[f];
       cout << " and v[" << f << "] = " << v[f] << endl;
   }

   return 0;
}


I played around with "Add watches" and I was not able to get a similar debugger output of a string vector compared to the output of a normal array (see screen-shot-1.png).

The only thing which was working for the string vector was the "element view" i.e. "Add wachtes --> v[0] (see screen-shot-1.png).

But  with this method you have to be very carefully, since if you enter a element which does not exist i.e. out of array range, you will get a "segmentation signal" from Code::Blocks. (see v[3] in "wachtes in screen-shot-1.png and signal in screen-shot-2.png). So for me this "element view" method is not a 100% good way, it is more a 80% provisional solution

However, it would be very convenient if the debugger would show the string vector similar like the array (see "a" in watches --> screen-shot-1.png).

Thanks

Martin

PS: @ Jens
special thanks to you for providing debian-repository for Code::Blocks.
I use Debain Lenny, and this is a very convenient way to be up to date with Code::Blocks nightly builds.
Small suggestion for your page http://apt.jenslody.de/ :

instead of this line:

--------------------------------------------------------------------------------------------

...The best and easiest way to add my public-key to apt's trustdb is to install the package jens-lody-debian-keyring with your preferred package-manager or apt-get.  ....

--------------------------------------------------------------------------------------------

write it more explicitly like:

--------------------------------------------------------------------------------------------

... The best and easiest way to add my public-key to apt's trustdb is to install the package jens-lody-debian-keyring with

#apt-get-get install jens-lody-debian-keyring

or

#aptitude  install jens-lody-debian-keyring

--------------------------------------------------------------------------------------------

Since most people do not read a web page they skim it.


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[taram]

Here screen-shot 2, since max. attachment size is 128kb

Martin

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[Jenna]

However, it would be very convenient if the debugger would show the string vector similar like the array (see "a" in watches --> screen-shot-1.png).

You are right, but that seems to be a gdb issue and a workaround might not be so easy.

PS: @ Jens
special thanks to you for providing debian-repository for Code::Blocks.
I use Debain Lenny, and this is a very convenient way to be up to date with Code::Blocks nightly builds.
Small suggestion for your page http://apt.jenslody.de/ :

(Vielen Dank)
Thank you for the suggestion, I just changed my site.

[taram]

Yes, it may be an GDB issue, but I have less knowledge about it.

However may be in a future nightly build this issue will be solved... may be this issue should be forwarded to a "GDB geek" of the Code::Blocks developer crew.

Cheers

Martin

[taram]

may be these links help....

http://www.stanford.edu/~afn/gdb_stl_utils/

http://help.lockergnome.com/linux/GDB-capabilities-exploring-STL-classes--ftopict279673.html

but this is beyond my "doable", since I am a newbe to GBD. hope some of the C::B developers can use this

cheers

Martin

[MortenMacFly]

Also frisch ans Werk - lets start fresh....
[...]
@ Jens: Schön, daß Du meinen Vorschlag aufgegriffen hast bzgl. Deiner HP. 

Although we do have German admins please do *not* post in German anymore if there is no particular reason. This is and remains an english-only forum. Thanks.

[taram]

?? I do not understand your concerns?? I know this fact, but there was no additional information in the German sentence and furthermore the translations was given directly behind it.

The other sentence was a thankful personal note to jens.

Further the complete discussion about the problem was/is done in English. If it would be done in German you would be right.

However, it was not my intention to disregard the forum rules, so I modified my entries above.

Cheers

Martin  

[rcoll]

Yes, it may be an GDB issue, but I have less knowledge about it.

However may be in a future nightly build this issue will be solved... may be this issue should be forwarded to a "GDB geek" of the Code::Blocks developer crew.

Cheers

Martin

No, I doubt it.  The GDB geeks are another group of geeks entirely.  The geeks who develope C::B only use GCC, they don't develope it.  In short, your problem is strictly a GDB problem, not a C::B problem.

I noticed that you never mentioned which version of GCC (and therefore GDB) you are using.  It may be that a newer version has the features you need.

Ringo

[taram]

thx ringo for your input. I use

- gcc version 4.3.2 (Debian 4.3.2-1.1,Target: i486-linux-gnu)   -- by $gcc -v

- GNU gdb 6.8-debian (This GDB was configured as "i486-linux-gnu".) -- by $gdb -v

I will try to find a deb package for debian lenny and then  update to GCC 4.3.3
   
http://gcc.gnu.org/gcc-4.3/

may be this solve the problem

cheers

Martin

[ollydbg]

You have to use the []-operator in your program, otherwise it gets not compiled in and therefore cannot be used by gdb.

Hi, Jens. Thanks for the reply.
I understand now. (Oh, My poor English, I need to read twice of these sentence to understand it's meaning )
If I define v[0], then gdb can also understand v[1].  

Code Select Expand


#include <iostream>
#include <string>
#include <vector>

using namespace std;

typedef vector<string> vstr;

int main()
{
   vstr v;
   v.push_back("bla bla");
   v.push_back("abcdef");

   string v0 = v[0];
   cout << "Hello world!" << endl;
   return 0;
}


See my screen shot.

Edit:
Oh, taram has already mentioned that.

Edit2
If I just add "v" to "watch", then check on the "Watch as array" opiotion. I still can't view any contents. Seems GDB didn't regard "v" as an array beginning address.
We can only use "v[0], v[1]" instead.





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