No Matching Constructor for Initialization on Mac

Question

I am learning c++ from Programming: Principles and Practice Using C++ / Edition 2 and I've run into a problem with vectors. I'm using the included header file provided from Stroustrup's book here. When I compile the following vector program, I get an error.

#include "std_lib_facilities.h"

int main()
{
    vector<int> v = {5, 7, 9, 4, 6, 8};
    for (int i=0; i<v.size(); ++i)
        cout << v[i] << endl;
}

Error

vector.cpp:5:21 error: no matching constructor for initialization of 'Vector<int>'
    vector<int> v = {5, 7, 9, 4, 6, 8};
                ^   ~~~~~~~~~~~~~~~~~~
./std_lib_facilities.h:82:5: note: candidate constructor template not viable: 
      requires 2 arguments, but 6 were provided
    Vector(I first, I last) :std::vector<T>(first, last) {}
    ^
./std_lib_facilities.h:79:14: note: candidate constructor not viable: requires 2 
      arguments but 6 were provided
    Vector(size_type n, const T& v) :std::vector<T>(n,v) {}
    ^
./std_lib_facilities.h:79:14: note: candidate constructor not viable: requires 
      single argument 'n', but 6 arguments were provided
    explicit Vector(size_type n) :std::vector<T>(n) {}
./std_lib_facilities.h:75:27: note: candidate constructor (the implicit move 
      constructor) not viable: requires 1 argument, but 6 were provided
    template< class T> struct Vector : public std::vector<T> {
                              ^
./std_lib_facilities.h:75:27: note: candidate constructor (the implicit copy 
  constructor) not viable: requires 1 argument but 6 were provided
./std_lib_facilities.h:78:5: note: candidate constructor not viable: requires 0 
      arguments, but 6 were provided
    Vector() { }
    ^

I'm compiling with: clang++ -std=c++11 -stdlib=libc++ vector.cpp

When I check my version of Clang, I get:

Apple LLVM Version 8.0.0 (clang-800.0.42.1)
Target: x86_64-apple-darwin16.1.0
Thread model: posse
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

I am having trouble making sense of the error and warnings and not sure where to go from here. Thank you for any insight you may provide.

@KerrekSB Stroustrup's `std_lib_facilities.h` has `#define vector Vector`. http://www.stroustrup.com/Programming/std_lib_facilities.h Can't say that I'm a fan of it, though... — krzaq, Nov 05 '16 at 19:37

score 1 · Accepted Answer · answered Nov 05 '16 at 19:46

std_lib_facilities.h defines class Vector<T> as:

template< class T> struct Vector : public std::vector<T> {
    typedef typename std::vector<T>::size_type size_type;

    Vector() { }
    explicit Vector(size_type n) :std::vector<T>(n) {}
    Vector(size_type n, const T& v) :std::vector<T>(n,v) {}
    template <class I>
    Vector(I first, I last) :std::vector<T>(first,last) {}

    T& operator[](unsigned int i) // rather than return at(i);
    {
        if (i<0||this->size()<=i) throw Range_error(i);
        return std::vector<T>::operator[](i);
    }
    const T& operator[](unsigned int i) const
    {
        if (i<0||this->size()<=i) throw Range_error(i);
        return std::vector<T>::operator[](i);
    }
};

// disgusting macro hack to get a range checked vector:
#define vector Vector

As you can see, there's no initializer_list constructor.

At this point, your options are limited.

You can eschew using std_lib_facilities.h
You can #undef vector after including std_lib_facilities.h

You can replace Vector class template constructors inherited constructors (using vector<T>::vector;):

template< class T> struct Vector : public std::vector<T> {
    typedef typename std::vector<T>::size_type size_type;

    using std::vector<T>::vector;

    T& operator[](unsigned int i) // rather than return at(i);
    {
        if (i<0||this->size()<=i) throw Range_error(i);
        return std::vector<T>::operator[](i);
    }
    const T& operator[](unsigned int i) const
    {
        if (i<0||this->size()<=i) throw Range_error(i);
        return std::vector<T>::operator[](i);
    }
};

Thanks for the quick answer, krzaq! I don't understand the header file yet so I'm not sure what using #undef vector does or what class template constructors are. I went ahead and replaced the `Vector` class template as you said, and it works. I'm just not sure what it is I replaced, and what I replaced it with. — mjdn, Nov 05 '16 at 20:05

score 0 · Answer 2 · edited May 23 '17 at 11:48

The linked header file has the line:

#define vector Vector

which means when you write vector<int> the compiler sees Vector<int>, which is his own implementation of a vector. I didn't see a constructor that builds an instance from a hard-coded array like you are trying to do.

If you include the actual standard library, it should work since you are compiling in C++11 (see here). Though that vector won't have the range checking added in the linked header file.

No Matching Constructor for Initialization on Mac

2 Answers2