Thread: Enum (Access violation) Crash

Hello All,

Small console code crashing when it reach to enum (T12::a4) variable. Same thing works fine on GUI.

error message:

(First-chance exception at 0x0F3FCAB4 (msvcr100d.dll) in ConsoleApplication2.exe: 0xC0000005: Access violation reading location 0x00000000.
If there is a handler for this exception, the program may be safely continued.)

Code:

funA()
{
char one[100] = "7a-11-2";
char two[100] = "19.32";
char three[25] = "hello";
char four[25] = "hello";

m_pVar = new T12::CClassA(two, one, three, four, T12::a4);
}

enum.h

Code:

namespace T12
{
enum em { a1 = 0, a2 = 1, a3 = 2, a4 = 3};
}

.h

Code:

namespace T12
{
CClassA
{
public:
CClassA(const std::string& two, const std::string& one, const  std::string& three, const std::string& four, em eVar);
};

}

How to solve this.
Answers Appreciated.

Way to provide an abundance of information. No one is going to be able to reproduce your error like this. Post something small that we can compile and look at ourselves. Look here for help in doing that.

For the shot in the dark answer you deserve, perhaps m_pvar was leaked by funA() - since it looks like you just create the object and fall off the end of the function. When you actually try to use m_pvar, boom!

Perhaps a debugger pointed you at the line of your mistake.

If you mean to write that funA returns a handle to an object then write that, and call it accordingly:

Code:

T12::CClassA *funA(void); // function prototype - void kept in for unambiguous sake

int main()
{
    T12::CClassA *handle = funA();
   // use handle
   delete handle; 
}

Compile with warnings on in the future too! I thought C++ was supposed to get rid of implicit return values....

> This is code should be clear
That still isn't a Short, Self Contained, Correct Example

Few will spend 10's of minutes guessing what all the missing code is in your snippet, only to fail to reproduce the issue you're facing.

Here's my 5 minutes.

Code:

#include <iostream>
#include <string>

namespace T12
{
  enum em { a1 = 0, a2 = 1, a3 = 2, a4 = 3};
}

namespace T12
{
  class CClassA
  {
    public:
      CClassA(const std::string& two, const std::string& one, const  std::string& three, const std::string& four, em eVar) {
      }
      CClassA* FunA();
  };
}

T12::CClassA* m_pVar;

int main()
{
  FunA(); //!!?? what
  return 0;
}

T12::CClassA* FunA()
{
  char one[100] = "7a-11-2";
  char two[100] = "19.32";
  char three[25] = "hello";
  char four[25] = "hello";
  m_pVar = new T12::CClassA(two, one, three, four, T12::a4);
}

Edit it so it
a) reproduces your problem
b) is something we can just copy/paste/compile and test in 30 seconds without wasting time guessing.

Whatever - post something we can copy/paste.

Originally Posted by whiteflags

Well, I had to remove a bunch of stray '\240' characters (not sure where they came from though)

\240 (0xa0) is the code for a non-breaking space in the Widows-1252 character set.

OP, this works:

Code:

#include <iostream>
#include <string>
  
namespace T12
{
  // If the values are just 0,1,2,3,... then they don't need to be specified.
  enum em { a1, a2, a3, a4 };
}
  
namespace T12
{
  class CClassA
  {
    public:
      CClassA(const std::string& two, const std::string& one,
              const std::string& three, const std::string& four, em eVar)
      {
      }
  };
}
  
namespace T12
{
  class CTemp
  {
  public:
    // FunA needs a return type.
    void FunA();
  };
}
 
T12::CClassA* m_pVar;
  
int main()
{
  // You need an object to call a non-static class member.
  T12::CTemp ct;
  ct.FunA();
  return 0;
}

// You need to specify the class that FunA belongs to.
void T12::CTemp::FunA()
{
  char one[100] = "7a-11-2";
  char two[100] = "19.32";
  char three[25] = "hello";
  char four[25] = "hello";
  m_pVar = new T12::CClassA(two, one, three, four, T12::a4);
}

> But when i create thw FunA() to DLL it is crashing at enum.
More drip-fed information, so now it's only a problem if a DLL is involved.

DLLs in Visual C++

After creating Dll, in main console, here it is crashing here.

Code:

m_pVar = new T12::CClassA(two, one, three, four, T12::a4);

Before posting, copy & paste the code you're going to post into a source file and compile.
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