Re: NULL

From:

Mohitz <coolmohitz@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Thu, 21 Jun 2007 17:33:36 -0700

Message-ID:

<1182472416.216515.275690@m37g2000prh.googlegroups.com>

Ya, the failure of the condition indicates a parse error. I want to
just print an intelligent
error message when that happens and want the program to exit. What's
the best way to do that?

Also, I am now trying to return a pointer but the program exits with a
segmentation fault. I am sorry
i am not quite good with pointers. Here is the code i am using. Is
something wrong with it?

ClassName * funcName(string name)
{
      deque<ClassName> tempDeque = someGlobalClassNameDeque;
      deque<ClassName>::iterator tempDequeIterate;
      tempDequeIterate = tempDeque.begin();
      while (tempDequeIterate != tempDeque.end())
      {
         ClassName * tempClassName = new ClassName();
         ClassName temp = *tempDequeIterate;
         *tempClassName = temp;
         if (name == temp->name)
                 return tempClassName;
         tempDequeIterate++;
      }
      return NULL;
}

int main()
{
        ClassName * p = funcName(someString);
        if (p == NULL)
        {
            parseError(someString + " undefined.");
        }
        else
        {
            toRet = anotherFunc(*p);
        }
        return toRet;
}

Any suggestions/comments would be appreciated.

Thank you,
Mohit

On Jun 22, 3:08 am, Rolf Magnus <ramag...@t-online.de> wrote:

Mohitz wrote:

How do you write a function in C++ which returns a class object in
some cases and in others, returns something like a NULL pointer so
that i can know in the callee function that the object doesnt exist??

ClassName A()
{
   ClassName a;
   if (condition)
        return a;
   else

throw some_exception();