# V5008\. OWASP\. Classes should always be derived from std::exception \(and alike\) as 'public'\.

Note: the diagnostic rule applies only to C\+\+\.

The analyzer has detected a class derived from the 'std::exception' class \(or similar classes\) via the 'private' or 'protected' modifier\. Such inheritance is dangerous because it may cause the failed catch of 'std::exception' during the non\-public inheritance\.

The error may occur if a developer has not specified the inheritance type\. According to the language rules, the inheritance is private by default\. As a result, exception handlers do not behave as intended\.

Here is the incorrect code:

```cpp
class my_exception_t : std::exception // <=
{
public:
  explicit my_exception_t() { }
  virtual const int getErrorCode() const throw() { return 42; }
};
....
try
  { throw my_exception_t(); }
catch (const std::exception & error)
  { /* Can't get there */ }
catch (...)
  { /* This code executed instead */ }
```

The code to catch all the standard and user exceptions, like 'catch \(const std::exception & error\)', cannot work properly because the private inheritance disables the implicit type conversion\.

To fix the code, add the 'public' modifier before the 'std::exception' parent class in the list of the base classes:

```cpp
class my_exception_t : public std::exception
{
  ....
}
```