cpp exception get the details of throw caller

Question

I have some custom exception like below

class myexception: public exception
{
  virtual const char* what() const throw()
  {
    return "My exception happened";
  }
} myex;

void testException(){
 throw myex;
}

void doSomething2(){
   testException();
}
void doSomething1(){
   doSomething2();
}


int main () {
  try
  {
    doSomething1();
  }
  catch (exception& e)
  {
    cout << e.what() << '\n';
  }
  return 0;
}

so in the main function I can not know the caller of a throw(which function has thrown exception), how to get that details ?

Possible duplicate of [Call-stack for exceptions in C++](https://stackoverflow.com/questions/3222890/call-stack-for-exceptions-in-c) — Aconcagua, May 25 '18 at 10:56
GCC specific: https://stackoverflow.com/questions/77005/how-to-automatically-generate-a-stacktrace-when-my-gcc-c-program-crashes — Aconcagua, May 25 '18 at 10:57
Why not write a meaningful message for exception, which includes name of throwing function? With C++11 you can use `__func__` to get the name of current function. — Yksisarvinen, May 25 '18 at 10:57
For debugging purpose you can set a breakpoint and look at the call stack. If you want in release also, maybe rethrow the exception like here http://www.cplusplus.com/reference/exception/rethrow_exception/. Dependent on you compiler, you could also use \__FUNCTION__ or \__FILE__ and \__LINE__ to throw in the `return` — MauriceRandomNumber, May 25 '18 at 10:58
In C++11 and later, there is a predefined macro `__func__` that can be used to obtain the name of the function in which it is called as a nul-terminated string (but not a string literal), and that can be passed to the constructor of your exception and a copy stored. Any answer for pre-C++11 compilers - if there is one - will be compiler specific, so you will need to specify your compiler. — Peter, May 25 '18 at 11:16
This link //https://panthema.net/2008/0901-stacktrace-demangled/ is also fine but, caller function name is not printed only address is printed — scoder, May 28 '18 at 15:56

score 1 · Answer 1 · answered May 25 '18 at 11:01

There are no easy portable ways to do this in C++ that I am aware of. There are some reasonably complicated ways to get full stack trace using Operating System specific calls.

The simplest way I use to get the source of the exception is using MACROS.

Macros are not recommended where they can be avoided but this is one of the few places they prove useful.

I tend to uses something slightly more complicated than this but this is the basics of it:

#ifndef NDBUG
#define throw_runtime_error(msg) \
    throw std::runtime_error(std::string(msg) \
        + " line: " + std::to_string(__LINE__) \
        + " file: " + std::string(__FILE__))
#else
#define throw_runtime_error(msg) throw std::runtime_error(msg)
#endif

void doSomething2(){
    throw_runtime_error("My runtime error.");
}
void doSomething1(){
   doSomething2();
}

int main()
{
    try
    {
        doSomething1();
    }
    catch(std::exception const& e)
    {
        std::cerr << e.what() << '\n';
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

You don't get a full trace but you do get to see where the exception was thrown. The MACRO only includes the debugging information when NDBUG is not set because release builds should set that macro to disable debugging information.

score 1 · Answer 2 · answered May 25 '18 at 11:02

1

this should be helpful:

How to automatically generate a stacktrace when my gcc C++ program crashes

you can find out way to print call stack and print that in exception handler.

answered May 25 '18 at 11:02

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Hi, when I run the example given in this function names are not printed, below is my output , /test/Example/Debug/backstrace[0x400749] /lib/x86_64-linux-gnu/libc.so.6(+0x36cb0)[0x7f1388167cb0] /test/Example/Debug/backstrace[0x4007a2] /test/Example/Debug/backstrace[0x4007ca] /test/Example/Debug/backstrace[0x4007d5] /test/Example/Debug/backstrace[0x400804] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7f1388152f45] /test/Example/Debug/backstrace[0x400669] – scoder May 28 '18 at 15:48
This link https://panthema.net/2008/0901-stacktrace-demangled/ is also fine but, caller function name is not printed – scoder May 28 '18 at 15:55

cpp exception get the details of throw caller

2 Answers2