C++ Adding new pointer objects to List

Question

I have a data structure defined up here called this:

   typedef list <classSpec*> ClassSpecList;

I'm trying to add stuff into the list here based on functions that return certain values of that match the same data type. In one function, I have a list pointer object defined here and I have another statement that calls a function.

 ClassSpecList *answer = 0;

 classSpec *thisanswer = parseClass(br);

Basically I'm trying to add the results of what thisanswer returns into my main ClassSpecList. Problem is, when I try

answer->push_back(new classSpec (*thisanswer));

It compiles but I get a seg fault

When I try somethign else like:

answer->insert(ClassSpecList.begin(), *thisanswer);

I keep getting primary expression errors and I do not know why. I even tried it with other list made without typedef and I still get those.

Thank you.

Answer 1

You should initialize the pointer answer first, like :

ClassSpecList *answer = new ClassSpecList;

then you can add thisAnswer into this list.

Answer 2

This should work:

ClassSpecList *answer = new ClassSpecList;
answer->push_back(thisAnswer);

as should this, which is usually recommended:

ClassSpecList answer;
answer.push_back(thisAnswer);

If possible, parseClass shouldn't return a pointer, and you should use typedef list <classSpec> ClassSpecList;.