member function question

This is a discussion on member function question within the C++ Programming forums, part of the General Programming Boards category; Here is a code listing from c++ primer plus. I don't understand how the copy constructor in this listing works ...

  1. #1
    Registered User
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    Apr 2002
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    member function question

    Here is a code listing from c++ primer plus. I don't understand how the copy constructor in this listing works

    Code:
    #include <iostream>
    using namespace std;
    #include <cstdlib>
    
    template <class T, int n>
    class ArrayTP
    {
         private:
              T ar[n];
         public:
              ArrayTP();
              explicit ArrayTP(const T & v);// cpy constructor proto type
              virtual T & operator[](int i);
              virtual const T & operator[](int i) const;
    };
    
    .
    .
    .
    .
     template <class T, int n>
    ArrayTP<T,n>::ArrayTP(const T & v)
    {
         for (int i=0; i<n; i++)
              ar[i]=v;                  //my question is here. i dont understand 
                                            // shouldnt it be ar[i]=v[i];
    }
    .
    .
    .
    .

  2. #2
    geek SilentStrike's Avatar
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    v is not an array, it's a value of type T (The ArrayTP class wraps a real array of T). That constructor initializes all the elements in the array to v. After the constructor, everything in the array will have the same value.
    Prove you can code in C++ or C# at TopCoder, referrer rrenaud
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  3. #3
    Registered User
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    95

    Thanks SilentStrike

    Thanks silentstrike!

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