Initialize static members in Template class

[INeedAHero]

I've been trying to initialize a static variable in my template class and I can't get it to work. The closest I've gotten is that the program compiles, outputs the correct information, but then immediately gives an error.

This is the relevant code:

#ifndef Array_h
#define Array_h

#include<iostream>
#include <cstdlib>
#include <iomanip>
using namespace std;

template <typename T>

class Array
{

     public:

//Array(T const& value = T());

        Array(int s = DEFAULTSIZE) // default constructor
        {
                cout << "dvalue is " << dvalue << endl;

                size = s;

                arr = new T [size];

                if(!arr)
                {
                        delete [] arr;
                        cerr << "error\n";
                        exit(EXIT_FAILURE);
                }
                for (int i = 0; i <= size; i++)
                {
                        arr[i] = dvalue;
                }

        }

And main.cpp

template<typename T> T Array<T>:: dvalue =9;

main()
{
        int size = 0;
        string yes_no;

        Array<int> a;
        cout << a << endl;
}

And this is the output:

dvalue is 9
9999999999
*** glibc detected *** ./a.out: free(): invalid next size (fast): 0x0000000001174010 ***
a.out: malloc.c:2453: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed.
Abort

[MrHutch]

The static initialisation is fine.

The problem could be your for loop. I'm guessing you might want < size rather than <= size.

[vlad from moscow]

I do not see the declaation of the static sata member dvalue. But in any case your program is invalid. For example instead of

for (int i = 0; i <= size; i++)
shall be

for (int i = 0; i < size; i++)

because you allocated size elements not size + 1 elements.

Also this code has no any sense

                if(!arr)
                {
                        delete [] arr;
                        cerr << "error\n";
                        exit(EXIT_FAILURE);
                }

First of all an exception will be generated if the memory will not be allocated. And if arr will be equal to 0 when this statement delete [] arr; has no any sense.

[INeedAHero]

Thanks guys

I do not see the declaation of the static sata member dvalue.

What do you mean? Where does that belong?


I corrected the silly error in the for loop, and now the program is running correctly.


And I also am aware that the if(!arr) code needs work; I'll be working on that soon.

[vlad from moscow]

@INeedAHero
What do you mean? Where does that belong?

All class members shall be declared inside the class definition.You are complaining that "I've been trying to initialize a static variable " and at the same time you did not show the declaration of sttatic data member dvalue.