Finding varible name by address in c++

Question

I need to find name of varible by address in c++. I have no idea about it for what code can i use ? Tell me how to fix this problem or is there any library in c++

(Slightly longer answer:) C++ is not a reflective language (like e.g. C#). At run-time, variable names are not available. The only exception is debug info which provides a mapping from addresses to symbols (incl. variable names) but that's an optional feature and compiler dependent. Beside of this, if reflection is needed (to a certain extent), it has to be implemented by custom (C++) code. — Scheff's Cat, Apr 25 '19 at 07:45
Please explain in details the initial problem you are trying to solve. Maybe it has another simpler solution. — vahancho, Apr 25 '19 at 07:47
This might be of interest: [SO: How can I add reflection to a C++ application?](https://stackoverflow.com/q/41453/7478597). This and more can be found by [google "stackoverflow c++ reflection"](https://www.google.com/search?q=stackoverflow+c%2B%2B+reflection) (to give you a start). — Scheff's Cat, Apr 25 '19 at 07:49
Most likely a [XY problem](https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem) (-> @vahancho). — Aconcagua, Apr 25 '19 at 07:54
Let u have adresses in which some binary is placed now the problem is we do not know that is it character type ,float type ,integer type or string type ?? — Mahar Ali, Apr 25 '19 at 07:54
Where does that data come from? You know, apart from alignment issues, *any* data could reside at *any* address. So if you don't have additional information, no chance. — Aconcagua, Apr 25 '19 at 07:55
Doesn't this problem exist only if you reverse-engineer binary code? (Only) one of the intentions of compiled code is the saving of intellectual properties... ;-) — Scheff's Cat, Apr 25 '19 at 07:55
@MaharAli Variable names in c++ are just hollow words. They won't be kept in the binaries (unless for debugging purposes). — πάντα ῥεῖ, Apr 25 '19 at 07:57
If it's really about de-compiling (-> @Scheff), then addresses won't serve you *anything at all*. You need to look at what the code in question *does* with this address (e. g. load value from memory address and add it on FPU stack -> data must be float or double). — Aconcagua, Apr 25 '19 at 07:58
@Aconcagua The intention of OP is still not clear. Otherwise, may be, I had mentioned [IDA](https://www.hex-rays.com/products/ida/index.shtml) as well... ;-) — Scheff's Cat, Apr 25 '19 at 08:00
@Scheff Hm, suppose I haven't made clear enough that it only was intended as example (but catching up your comment); should (only) enlighten a bit more that addresses on their own are useless... Almost at least (odd address most likely won't be `int`...). — Aconcagua, Apr 25 '19 at 08:03

score 1 · Answer 1 · answered Apr 25 '19 at 08:06

If you mean to find the string that specifies the name of some arbitrary variable(class member or local) by the memory address at runtime - the answer is no for several reasons:

In the binary without symbols there is just no information about the original names of variables and classes.
I guess in a run-time library implementation objects do not contain any extra information to find that this address corresponds to a certain object in the runtime. For objects of classes without virtual table you even can't know the actual type in runtime.

If the question is about more specific situation - when you have an address that corresponds to an object of the known base address of a certain type - yes it could be implemented by comparing the address with pointer to members. Example:

struct Foo
{
    int Member1;
    double Member2;
};

enum class Member
{
    Member1,
    Member2,
    None
};

Member getMember(const Foo* baseAddress, void* address)
{
    if (address == &(baseAddress->Member1))
    {
        return Member::Member1;
    }
    else if (address == &(baseAddress->Member2))
    {
        return Member::Member2;
    }
    else
    {
        return Member::None;
    }
}

Finding varible name by address in c++

1 Answers1