Question

I’m a newbie at using the STL Algorithms and am currently stuck on a syntax error. My overall goal of this is to filter the source list like you would using Linq in c#. There may be other ways to do this in C++, but I need to understand how to use algorithms.

My user-defined function object to use as my function adapter is

struct is_Selected_Source : public std::binary_function<SOURCE_DATA *, SOURCE_TYPE, bool>
{
bool operator()(SOURCE_DATA * test,  SOURCE_TYPE ref)const
    {
    if (ref == SOURCE_All)
        return true;
    return test->Value == ref;
    }
};

And in my main program, I’m using as follows –

typedef std::list<SOURCE_DATA *> LIST;
LIST; *localList = new LIST;;
LIST* msg = GLOBAL_DATA->MessageList;
SOURCE_TYPE _filter_Msgs_Source = SOURCE_TYPE::SOURCE_All;

std::remove_copy(msg->begin(), msg->end(), localList->begin(),
    std::bind1st(is_Selected_Source<SOURCE_DATA*, SOURCE_TYPE>(), _filter_Msgs_Source));

What I’m getting the following error in Rad Studio 2010. The error means “Your source file used a typedef symbol where a variable should appear in an expression. “

“E2108 Improper use of typedef ‘is_Selected_Source'”

---

Edit –
After doing more experimentation in VS2010, which has better compiler diagnostics, I found the problem is that the definition of remove_copy only allows uniary functions. I change the function to uniary and got it to work.

Answer 1

(This is only relevant if you didn’t accidentally omit some of your code from the question, and may not address the exact problem you’re having)

You’re using is_Selected_Source as a template even though you didn’t define it as one. The last line in the 2nd code snippet should read std::bind1st(is_Selected_Source()…

Or perhaps you did want to use it as a template, in which case you need to add a template declaration to the struct.

template<typename SOURCE_DATA, typename SOURCE_TYPE>
struct is_Selected_Source : public std::binary_function<SOURCE_DATA *, SOURCE_TYPE, bool>
{
    // ...
};