# V759. Violated order of exception handlers. Exception caught by handler for base class.

The analyzer detected multiple exception handlers arranged in a wrong order. The handler for base-class exceptions is placed before the handler for derived-class exceptions; therefore, every exception that must be caught by the derived-class handler will be caught by the base-class handler.

Consider the following example:

    class Exception { .... };
    class DerivedException : public Exception { ... };
    void foo()
    {
      throw DerivedException;
    }
    void bar()
    {
      try
      {
        foo();
      }
      catch (Exception&)
      {
        // Every exception of type DerivedException will get here
      }
      catch (DerivedException&)
      {
        // Code of this handler will never execute
      }
    }

Since 'Exception' is the base class for the 'DerivedException' class, all exceptions thrown by the 'foo()' function are caught by the first handler.

To fix this error, we need to swap the handlers:

    void bar()
    {
      try
      {
        foo();
      }
      catch (DerivedException&)
      {
        // Catches exceptions of type DerivedException
      }
      catch (Exception&)
      {
        // Catches exceptions of type Exception
      }
    }

With this fix, each handler will catch only those exceptions it was meant to.

This diagnostic is classified as:

CWE-703 CERT-ERR54-CPP