How to get value of a data member in gdb?

Question

Hi I am currently debugging my code base in linux machine through GDB. I am currently facing an issue in getting value of a data member from object ptr of a class. To print the location for object ptr we can use either "p" (print) or "display" command.

For Eg: I have class like this

class abc
{
    string a;
};

So in my code if I am using a pointer for class abc, then

abc* objPtr = new abc();

so after breaking at above line i will get objPtr and now I want to check value of datamember a (abc::a) value. how I could do that?

(gdb) p objPtr
$2 = {px = 0x3ba6430690, pn = {pi_ = 0x3ba6430698}}

Moreover Is there a different way to check a data member which is a list / vector ?

Regarding your list/vector question, have a look here: http://stackoverflow.com/questions/427589/inspecting-standard-container-stdmap-contents-with-gdb — Nobody moving away from SE, May 30 '12 at 10:19
That gdb output looks like a boost::shared_ptr not abc*, so try print *objPtr->px or print objPtr->px->a — Jonathan Wakely, May 30 '12 at 18:09

score 2 · Answer 1 · answered May 30 '12 at 10:36

2

I got the answer.

$p/a objPtr->datamember->[if datamember also has some data member then we can call it in recurcion / can also call member function].

for list/vector we could refer to http://sourceware.org/ml/gdb/2008-02/msg00064/stl-views.gdb.

answered May 30 '12 at 10:36

Apoorva sahay

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score 0 · Answer 2 · answered May 30 '12 at 10:12

0

You can try:

$ p abc->c_str()

answered May 30 '12 at 10:12

unwind

378,987
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590

You missed the `a` and used the type instead of the instance: `objPtr->a.c_str();` – Nobody moving away from SE May 30 '12 at 10:12
what if I want to check a list which is datamember for class abc? – Apoorva sahay May 30 '12 at 10:18
Note: calling functions only work while attached to a process, not while inspecting a core (it's a limitation to keep in mind). – Matthieu M. May 30 '12 at 12:09

score 0 · Answer 3 · answered Apr 27 '21 at 20:14

0

p objPtr->a

will print the data member type and value of variable a

answered Apr 27 '21 at 20:14

SunDontShine

118
1
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How to get value of a data member in gdb?

3 Answers3