Thread: vector delete not functioning...

  1. #1
    Registered User
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    vector delete not functioning...

    My delete is not working. Why?

    Code:
    struct MatchName
    {
        MatchName(string& searchName) : s_(searchName) {}
        bool operator()(const clsStudent* student) const
        {
            return student->getName() == s_;
        }
        private:
        string s_;
    };
    
    void deleteStudent(vector <clsStudent*>& student)
    {
        string nameToDelete;
        if (!(student.empty()))
        {
            cout << "\nEnter name of student to delete: " << endl;
            cin >> nameToDelete;
            remove_if(student.begin(), student.end(), MatchName(nameToDelete));
            cout << "Student " << nameToDelete << " deleted.";
        }
        else{
            cout << "\nUnable to perform selected action.";
            cout << "\nThere is " << student.size() << " of students to delete\n" ;
        }
    }

  2. #2
    C++ Witch laserlight's Avatar
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    You need to call the erase member function to erase the element(s) removed. Otherwise, the element(s) will be removed from the vector's range of elements to be used, but will remain as an element of the vector.
    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
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    On a side note shouldn't you verify the student does indeed exist within the vector before attempting to delete it?

  4. #4
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by Ewiv
    shouldn't you verify the student does indeed exist within the vector before attempting to delete it?
    That's effectively what remove_if does when used in conjunction with erase.
    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

  5. #5
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    Quote Originally Posted by laserlight View Post
    That's effectively what remove_if does when used in conjunction with erase.
    Ok, I just looked up erase to expand my own understanding in C++. I see what your saying now. Erase will fix his problem as well as what I was seeing as a possible problem in the future.

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