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Where does the SIGABRT get raised? You may need to add your own signal handler to trap it and take action accordingly.
One of these days I'm going to think of a really clever signature.
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It is raised at the point where the exception is thrown. As you can see, unless I am totally missing something, the int is being thrown and properly caught so there should not be a signal raised at all. This is my dilema.
I put in a signal handler but it does no good. App still closes. I will need to handle the signals eventually since this is a unit tester. But for now, I am just trying to figure out why the SIGABRT could possibly be raised on a legitimate thrown and caught exception
This is the message at runtime:
terminate called after throwing an instance of 'int'
The program has unexpectedly finished.
Basically it acts as if there is no catch and the terminate is called. Or perhaps I am misreading something. The stack dump is below
0 __kernel_vsyscall 0 0xb7fdd424
1 __GI_raise raise.c 64 0xb7bd61ef
2 __GI_abort abort.c 91 0xb7bd9835
3 __gnu_cxx::__verbose_terminate_handler() /usr/lib/i386-linux-gnu/libstdc++.so.6 0 0xb7e1813d
4 ?? /usr/lib/i386-linux-gnu/libstdc++.so.6 0 0xb7e15ed3
5 std::terminate() /usr/lib/i386-linux-gnu/libstdc++.so.6 0 0xb7e15f0f
6 __cxa_throw /usr/lib/i386-linux-gnu/libstdc++.so.6 0 0xb7e1605e
7 UtilStrTrimTests::UTL_STR_RTRIM_1 mr_util_str_trim_tests.cpp 31 0xb7b6d692
8 MrTest::Fixture::ExecStep CppTestFixture.cpp 178 0xb7f56d2a
9 MrTest::Fixture::RunTest CppTestFixture.cpp 160 0xb7f56c3c
10 MrTest::EngineImplementation::RunAllFixtureTests MrTestEngineImplementation.cpp 350 0xb7f71a89
11 MrTest::EngineImplementation::ProcessTestList MrTestEngineImplementation.cpp 227 0xb7f711fc
12 MrTest::Engine::ProcessTestList CppTestEngine.cpp 57 0xb7f48241
13 main CppTestDevConsole.cpp 94 0x804cb5c
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I found a solution to the SIGABRT problem. As I suspected it was a problem with the makefile. In particular, I changed
this:
ld -shared -soname $@ -o $@ $(OBJS)
to this:
$(CC) -shared -W1,-soname,$@ -o $@ $(OBJS)
It now behaves in the same way as in Windows. As long as I catch the exception properly it will never SIGABRT.
Seeing that I am not a linux guru, I would appreciate if someone out there has an explanation why a shared object linked with ld will not allow exceptions while one linked with gcc will.
It may also help anyone else having a similar problem. I looked far and wide and could find no documentation on this.
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Can anyone please explain me how to build and use cppunit in visual studio 2010?
I have tried a lot but not able to get it..
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Not sure if this will help, but look at this article[^]. 
Chris Meech
I am Canadian. [heard in a local bar]
In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]
posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]
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Rahul from Poona wrote: I have tried a lot but not able to get it..
Presumably you are using unmanaged C++ right?
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Hello. I am little confused in Late Binding Concept (although I understand it theoretically) as I could not understand it programatically. I am defining two classes here and then casting and using their pointers.
CBaseClass
<br />
void CBaseClass::Function()
{<br />
cout<<"\nBase Class.";<br />
}<br />
CChildClass
<br />
void CChildClass::Function()
{<br />
cout<<"\nChild Class.";<br />
}<br />
MainClass
<br />
void main()<br />
{<br />
CBaseClass* pBase = new cBaseClass();<br />
CChildClass* pChild = (CChildClass*)pBase;<br />
<br />
pBase->Function();<br />
pChild->Function();<br />
}<br />
What should the two function calls produce in MainClass. I think it should produce
BaseClass.
ChildClass.
But it actually produces
BaseClass.
BaseClass.
What is wrong with my understanding. Thanks
This world is going to explode due to international politics, SOON.
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The right main function ought be:
void main()
{
CBaseClass* pBase1 = new cBaseClass();
CBaseClass* pBase2 = new cChildClass();
pBase1->Function();
pBase2->Function();
}
Veni, vidi, vici.
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I just tried this and it produces the expected output:
Base Class.
Child Class.
One of these days I'm going to think of a really clever signature.
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It maybe but
Are you sure? What compiler are you using? What code? What else? 
Anyway
CBaseClass * pBase = new CBaseClass();
CChildClass * pChild = (CChildClass *) pBase;
is a gross mistake.
Veni, vidi, vici.
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Exactly so, but as so often happens, the OP has only given us part of the story.
One of these days I'm going to think of a really clever signature.
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The code you have shown above does not match the code you are using. If I change it to the following, then it produces the results that you see.
class CBaseClass
{
public:
virtual void Function() {
cout<<"\nBase Class.";
}
};
class CChildClass : CBaseClass
{
public:
void Function() {
cout<<"\nChild Class.";
}
};
One of these days I'm going to think of a really clever signature.
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The bug in your code is obvious. CPallini already gave you the correct code but I feel this is something that needs further clarification.
The bug is the following, and its a major bug in its current context:
CChildClass* pChild = (CChildClass*)pBase;
There are 2 kinds of static casts: downcast and upcast. If you are drawing the uml diagram of your class hierarchy then it looks like a tree with its root node (base class) at the top of the diagram. Down and upcast are named based on the direction of the cast in this tree so an upcast means that you cast a derived class to one of its base classes in the hierarchy, this type of cast is safe, you don't have to mark it explicitly in your code because the compiler does it automatically for you:
Derived * d = new Derived;
Base* b = d;
However downcasts are not only dangerous but they usually mean that you committed a design mistake. A base class can have a lot of derived classes and if you are casting a base class to one of its derived classes than its a bug if the actual object isn't an instance of the downcast type or its descendants. People often say that dowcasts defeat the whole purpose of polymorphism/late binding. Example:
class Base;
class A : public Base;
class B : public Base;
Base* b = new B;
A* p = (A*)b;
So why doesn't your code crash??? Because you were lucky and currently in your simple example the binary representation of instances created by the compiler for your base and derived classes are probably identical, they just differ in their vtable pointer but in any more complex situations it could easily crash.
OK, so when you have a complex hierarchy and you call a virtual function on a base class pointer then which method is executed??? It depends on which object have you actually created! (with new). Since in your example you created just a Base instance it would be magic to see executing the method of the derived class, and its just luck that using the pointer that you filled with your invalid downcast haven't crashed your program.
So based on what we have learned up until now you should only use upcasts that are done automatically for you by the compiler, for example:
CBaseClass* p = new CChildClass; p->Function();
Describing the same in other words:
You can always use a base class pointer to point to an object that was created by instantiating a class derived from the base class. This way if you call some virtual methods on the base class pointer then the methods of the actually instantiated class are called.
modified 24-Sep-12 14:17pm.
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Veni, vidi, vici.
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Good explanation about the perils of upcasting and downcasting and how in this simple example the downcasting worked, but that in a real world case, it would likely crash.
Chris Meech
I am Canadian. [heard in a local bar]
In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]
posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]
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+5. Great explanation. For me too, I've been reversing upcast and downcast terms, didn't think of the diagram. Saw the obvious error in his example though.
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Regarding the upcast/downcast naming: A lot of coders exchange these names so when someone starts using them I always ask him to clarify how to interpret "his upcast" right at the start of the conversation. I also used them in reverse order for a long time until reading some uml docs that clarified it for me. For some reason thinking that upcast is casting up to a higher level smarter derived class seemed to be more logical for me.
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Which is how I use "upcast", to a "bigger" container, the derived class. Of course, that's just a convenience notation. The real idea is
Cast Derived to Base - OK
Cast Base to Derived - Bad
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Hi, have a good day
I am using Already built DLL , with callback function inside it :
After I execute this code my application freeze ( SomeCallback : read only once ) and freeze
I don't know what is wrong ?
DLL Define code ( DLL is open source ) :
typedef int __stdcall cbtype (char *what, Number int1, Number int2, char *str);
extern "C" int __cdecl FreeArcExtract (cbtype *callback, ...);
My Code :
#include <cstdlib>
#include <iostream>
#include "windows.h"
using namespace std;
typedef bool (*cbtype) (char *what, int, int, char *str);
bool SomeCallback( char *c1 , int i1 , int i2, char *c2)
{
printf("%s\r\n" , c1);
printf("%d\r\n" , i1);
printf("%d\r\n" , i2);
printf("%s\r\n" , c2);
return true;
}
void ArcExtract ()
{
HINSTANCE GetProcDLL = LoadLibrary("unarc.dll");
FARPROC GetProcessID = GetProcAddress(
HMODULE (GetProcDLL), "FreeArcExtract");
typedef int (__cdecl * CallingFun)(cbtype, LPCTSTR , LPCTSTR, LPCTSTR , LPCTSTR,LPCTSTR , LPCTSTR,LPCTSTR , LPCTSTR,LPCTSTR , LPCTSTR);
CallingFun FreeArcExtract;
FreeArcExtract = CallingFun(GetProcessID);
FreeArcExtract((cbtype)SomeCallback,
"l", "--", "d:\\test.arc", "", "", "", "", "", "", "");
FreeLibrary(GetProcDLL);
}
int main(int argc, char *argv[])
{
ArcExtract ();
return EXIT_SUCCESS;
}
I think the error are in the call back function
I write the same code on C# and it's work like charming.
with same dll , and the same d:\test.arc
C# Code :
class ArcArchive
{
public delegate bool unarcCallBack(string what, int param1, int param2, string text2);
[DllImport("unarc.dll")]
public static extern int FreeArcExtract(unarcCallBack callback,
string cmd1, string cmd2, string cmd3, string cmd4, string cmd5, string cmd6, string cmd7, string cmd8, string cmd9, string cmd10);
}
static void Main(string[] args)
{
ArcArchive.unarcCallBack ArcCallBack = new ArcArchive.unarcCallBack(CallBackFunction);
ArcArchive.FreeArcExtract(ArcCallBack,
"l", "--", "d:\\test.arc", "", "", "", "", "", "", "");
}
static bool CallBackFunction(string what, int param1, int param2, string t2)
{
Console.WriteLine(what);
Console.WriteLine(param1);
Console.WriteLine(param2);
Console.WriteLine(t2);
return true;
}
please is there is anyway to write callback function in c++ ? or is my c++ code had some logical errors.
Thank you
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You have mixed up a lot, specially with typedef and function pointer definition and usage. To understand function pointer definition clearly read about Function Pointer[^]. Also look at wiki link[^] to learn about typedef in detail.
To solve your problem
1. write include of windows.h as
#include <windows.h>
and it has nothing to do with your problem
2. If you have the .lib file then it is great just include the header file as below:
#include "the_header_file.h"
and also include the library file with your project.
if you dont have then follow the code it might help:
#include <cstdlib>
#include <iostream>
#include <windows.h>
using namespace std;
typedef bool (*cbtype) (char *what, int, int, char *str);
bool SomeCallback( char *c1 , int i1 , int i2, char *c2)
{
printf("%s\r\n" , c1);
printf("%d\r\n" , i1);
printf("%d\r\n" , i2);
printf("%s\r\n" , c2);
return true;
}
void ArcExtract ()
{
HINSTANCE GetProcDLL = LoadLibrary("unarc.dll");
if(GetProcDLL==NULL)
{
}
typedef int (__cdecl * CallingFun)(cbtype, ...);
CallingFun FreeArcExtract;
FreeArcExtract =(CallingFun) GetProcAddress(HMODULE (GetProcDLL), "FreeArcExtract");
if(FreeArcExtract==NULL)
{
}
FreeArcExtract((cbtype)SomeCallback,
"l", "--", "d:\\test.arc", "", "", "", "", "", "", "");
FreeLibrary(GetProcDLL);
}
int main(int argc, char *argv[])
{
ArcExtract ();
return EXIT_SUCCESS;
}
I wish I could believe there is an after life.
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Thank you Sir, I have Solved the problem
Here is the Fixed Code
#include <cstdlib>
#include <iostream>
#include <windows.h>
using namespace std;
typedef int __stdcall cbtype (char *what, int int1, int int2, char *str);
int __stdcall somecallback (char *what, int int1, int int2, char *str)
{
cout << what << endl;
cout << int1 << endl;
cout << int2 << endl;
cout << str << endl;
}
void ArcExtract ()
{
HINSTANCE GetProcDLL = LoadLibrary("unarc.dll");
FARPROC GetProcessID = GetProcAddress(HMODULE(GetProcDLL), "FreeArcExtract");
typedef int (__stdcall * CallingFun)(cbtype, ...);
CallingFun FreeArcExtract;
FreeArcExtract = CallingFun(GetProcessID);
FreeArcExtract(somecallback,"l", "--", "d:\\test.arc", "", "", "", "", "", "", "");
FreeLibrary(GetProcDLL);
}
int main(int argc, char *argv[])
{
ArcExtract ();
system("pause");
return EXIT_SUCCESS;
}
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