Appending/Concatenating strings

I'm using a recursive implementation which has a method toString() that returns a string (concatenated or appended) by all the values in my tree. Unfortunately when I try using "+=" or the old "string = string + otherString" all it seems to do is override the original. Giving me a single value instead of all of them. When I replace it with "cout << " then all the values print. I have #include <string>, so I should be able to do that right?

Code:

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//Note: toString() returns a string representation of any value being stored in the tree
//          such as integers, floats etc... and works fine.
string Node::print()
{
        string result;

        //travel left
        if( this->getLeft() != NULL )
        {
                this->getLeft()->print();
        }

        //Keep track of values
        result += this->getValue()->toString(); //doesn't store all the values
        //cout << this->getValue()->toString(); //prints all the values

      //travel right
        if( this->getRight() != NULL )
        {
                this->getRight()->print();
        }

        return result;
}

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The trouble is that each instance of print() has its own result variable. You need to use only one variable, if I'm understanding you correctly. Perhaps passing one result as a reference might do the trick.

Shouldn't this:

Code:

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this->getLeft()->print();

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be more like this:

Code:

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result += this->getLeft()->print();

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>> The trouble is that each instance of print() has its own result variable.
That shouldn't be a problem as long as the fix cpjust mentioned is implemented.

oh, ha I suppose your right. Sometimes I don't analyze a recursive implementation as much as I would an iterative one. Thanks guys, works like a charm.

What about casting into an object I created, like in java? Say you have a generic hierarchy item which you want to cast in order to use a specific class's methods? In java you just do (myObject)Node.getValue() and your done. Can I do that in C++?

Yes, dynamic_cast. But most uses of that indicate a design problem.

For data structures like trees or lists, which is what your code looks like, you'd use templates.

Quote:

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Originally Posted by John_L

oh, ha I suppose your right. Sometimes I don't analyze a recursive implementation as much as I would an iterative one. Thanks guys, works like a charm.

What about casting into an object I created, like in java? Say you have a generic hierarchy item which you want to cast in order to use a specific class's methods? In java you just do (myObject)Node.getValue() and your done. Can I do that in C++?

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Yuk! You don't really want to model your C++ programs after Java's sloppy style do you?