Thread: weird compile error

  1. #1
    Registered User
    Join Date
    Jul 2009

    weird compile error

    template <class C, class T> int count2(const C &v, T val)
        C::const_iterator i = find(v.begin(), v.end(), val);
        int n = 0;
        while(i != v.end()) {
            i = find(i, v.end(), val);
        return n;
    This functions counts the number of occurences of 'val' inside the type C.

    What i dont understand is why do i get compile error for this that i is undeclared...
    Last edited by Tool; 06-23-2010 at 04:15 PM.

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    The problem that I see is that C::const_iterator is a name dependent on the template parameter C, hence it should be disambiguated with typename otherwise it would be assumed to be a member name instead of a type name, i.e.,
    typename C::const_iterator i = find(v.begin(), v.end(), val);
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    Cat without Hat CornedBee's Avatar
    Join Date
    Apr 2003
    Mind you, if this isn't merely an exercise, there's a std::count that already does what you want.
    All the buzzt!

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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