problrm with array in c++ - c++

Question

this is my Stata.h
#include "State.h"
#include <iostream>
using namespace std;
class State
{
public:
int data[4][4];
int x;
int y;
int cost[];
State(void);
void CopyState(State*);
bool equals(State*);
int h(State*);
void print(void);
private:
int getLocation(State, int, int);
};
and this is my State.cpp
#include "State.h"
#include <iostream>
using namespace std;
State::State(void)
{
State::cost[] = {0, 3, 2, 5, 3, 4, 1, 2, 2, 1, 4, 3,
5, 2, 3, 2, 3, 0, 3, 2, 2, 3, 2, 1,
1, 2, 1, 4, 2, 3, 2, 3, 2, 3, 0, 3,
1, 2, 3, 2, 4, 1, 2, 1, 3, 2, 3, 2,
5, 2, 3 ,0 ,2 , 1 , 4 , 3 ,3 , 4 ,1 , 2,
2, 3, 2, 5, 3, 2, 1, 2, 0, 3, 2, 3,
3, 2, 1 ,2 ,2 , 1 ,4 ,3 , 4 ,3 ,2 , 1 ,
3 ,0, 3, 2, 2 , 3, 2, 1 , 1 , 2, 1, 4,
1 , 2, 3 ,4 ,2 ,3 ,0 ,3 ,1 , 2 ,3 ,2 ,
4 ,1, 2, 1, 2, 1, 2, 3, 3, 2, 3, 0,
2 ,1, 2 , 3 ,3 ,4 ,1 ,2 , 2 , 1 ,4 ,3,
3 , 2, 1, 2, 0 , 3 , 2 , 3, 3 , 2, 1, 2,
1 ,2, 1 , 4 ,2 ,3 ,2 , 1 , 3 , 0 , 3 , 2,
4 , 3, 2 , 1 , 4 , 1, 2 , 1 , 1 , 2, 3 , 2,
2, 3 ,0 ,3 ,1 , 2 , 3 , 4 , 3 ,4 , 1 ,2,
2 ,1, 2, 3 , 3 , 2 , 3 , 0, 2, 1, 2, 3,
5 , 2 ,3 , 2 ,2 ,1 , 4 ,3 ,3 ,4 ,1 ,2,
0 ,3, 2, 5, 2 , 3 , 2, 3, 1, 2, 1, 4,
2 ,3 ,2 , 1 ,3 , 0 ,3 , 2, 3 , 2 ,3 ,2 ,
4 ,1, 2, 1, 1 , 2, 3 , 2 , 2, 3 , 0, 3,
2 ,3 ,2 , 5 , 3 , 4 , 1 , 2 , 2 , 1 ,4 , 3 ,
5 , 2 ,3 ,0
};
}
void State::CopyState(State *state)
{
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
data[i][j] = state->data[i][j];
x = state->x;
y = state->y;
}
bool State::equals(State *state)
{
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
if (data[i][j] != state->data[i][j])
return false;
return true;
}
int State::h(State *state)
{
int k = 0;
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
{
int frmPos = 4 * i + j;
int toPos = getLocation(*state, i, j);
k += cost[16 * frmPos + toPos];
}
return k;
}
void State::print()
{
cout << "\n";
for (int i = 0; i < 4; i++)
{
cout << "\n";
for (int j = 0; j < 4; j++)
cout << data[i][j];
}
cout << endl;
}
the problem is in State.cpp in the constructor when I'm trying to assign values to the cost array I don't know where is the problem, please any one can solve that , sorry for my bad english

Answer 1

You can't do it that way. There's a couple of problems, but the first problem is this:
In the header you declare cost as an array with an unspecified size:
int cost[];
This isn't allowed in Standard C++ because now the compiler doesn't know how big the array is, and therefore doesn't know how big State will be. (Some compilers do allow it, but it's a special extension that won't work on other compilers.)
The simplest and often best way to do this is to use a vector:
#include <vector>
class State
{
// ...
std::vector <int> cost;
};
And then in the constructor:
State::State()
{
static const int startingValues [] =
{0, 3, 2, 5, 3, 4, 1, 2, 2, 1, 4, 3, ... };
static const size_t numStartingValues = sizeof (startingValues) / sizeof (startingValues [0]);
std::copy (startingValues, startingValues + numStartingValues, std::back_inserter (cost));
}
If you're using C++11, then this is made simpler with the uniform initialization syntax:
State::State()
:
cost {0, 3, 2, 5, ...}
{
}

Answer 2

First of all, the cost member is not an array, it is a pointer (or it was when I looked at it, but you've changed it. However, it's still not an array. It is now a compiler error.). If you want it to point to an array, first you have to allocate it. But that's a terrible idea. Change it to a vector:
class State {
...
std::vector<int> cost;
...
};
Then, in your constructor, you can initialize it like this (if your compiler supports C++11)
State::State() :
cost{0, 3, 2, 5, 3, 4} // trimmed for brevity, but you can put as many elements as you want
{}
If your compiler does not support C++11 (or does not support this feature), then you can initialize the vector like this:
State::State()
{
static int temp[] = {0, 3, 2, 5, 3, 4};
cost.assign(temp, temp + sizeof(temp) / sizeof(*temp));
}