C++ 从未命名命名空间调用函数时出错

问：

我正在尝试完成初学者 comp sci 的作业。我们只是在学习空间分配和使用标头，以及动态内存分配。其中一个要求是，我们必须在 const 变量和函数声明的标头中使用未命名的命名空间。我在第 28 行收到一个关于“未定义对匿名命名空间的引用”的编译错误，我不确定如何解决这个问题或是什么语法或拼写错误导致了它。我们只是在学习这个，所以不要太苛刻地判断哈哈。

我的图书馆.hpp

#include <iostream>
#include <memory>

#ifndef MYLIBRARY_HPP
#define MYLIBRARY_HPP

namespace
{
    int counter = 0;
    const int SIZE = 10;
    std::unique_ptr<char[]> deleteRepeats(char arr[]);
}

#endif // MYLIBRARY_HPP

主 .cpp

using std::cin;
using std::cout; //using declarations to avoid namespace std
using std::endl;

int main()
{
   
    char originalArray[SIZE]; //declaration of array that will be used in the program and all its values
    originalArray [0] = 'a';
    originalArray [1] = 'b';
    originalArray [2] = 'b';
    originalArray [3] = 'c';
    originalArray [4] = 'a';
    originalArray [5] = 'c';
    originalArray [6] = 'a';
    originalArray [7] = 'c';
    originalArray [8] = 'b';
    originalArray [9] = 'c';
    std::unique_ptr<char[]> noRepeats = deleteRepeats(originalArray); //function call

    cout << "the amount of repeats is... " << SIZE-counter << endl; //prints out the number of repeats

    for(int i =0; i<counter; i++) //displays new array
    {
        cout << noRepeats[i] << endl;
    }

    return 0;
}

函数：.cpp

#include <iostream>
#include <memory>

//my function definitions
namespace
{
    //Precondition: an array of defined size contains only valid characters
    //Postconition: a new array is generated with only unique values
    std::unique_ptr<char[]> deleteRepeats(char arr[]) //goes through the array and checks if it has repeats
    {
        for(int i=0; i<SIZE/2; i++)
        {
            if(arr[i] = arr[SIZE -1-i]) //marks any repeats
            {
                arr[i] = '-';
                arr[SIZE-1-i] = '-';
            }
        }
        for(int i =0; i<SIZE; i++) //counts new array
        {
            if(arr[i] != '-')
            {
                counter++;
            }
        }
        std::unique_ptr<char[]> newArray(new char[counter]); //declares a new array using a pointer
        int location = 0;
        for(int i = 0; i<SIZE; i++)
        {
            if(arr[i] != '-')
            {
                newArray[location++] = arr[i];
            }
        }
        return newArray;
    }
}