I've just tried:
class Test
{
public:
int iArray[][];
}
...is this not possible? Do I have to set a constant value?
like:
class Test
{
public:
const int iArray[5][4];
}
I want to define [x][y] later, just have the placements there. Else it wouldn't be "dynamic" and I don't want to use a vector because I want to be able to access the values by "X" and "Y".
I think better way to achieve this is to use pointers. You can do like this.
#include <cstdlib>
#include <iostream>
using namespace std;
class PointerTest {
private:
int** array;
int x, y;
public :
void setValue(int row, int col,int value);
int getValue(int row, int col);
PointerTest(int row, int col);
~PointerTest() {
for(int i=0;i<x;i++) {
delete array[y];
}
}
};
PointerTest::PointerTest(int row, int col) {
x=row, y=col;
for(int i=0;i<row;i++) {
*array=new int[col];
}
}
void PointerTest::setValue(int row, int col, int value) {
*(array[row])=value;
}
int PointerTest::getValue(int row, int col) {
return *(array[row]);
}
int main(int argc, char *argv[])
{
PointerTest* t=new PointerTest(4,5);
t->setValue(0,0,464);
cout<<"The value in array: "<<t->getValue(0,0)<<endl;
system("PAUSE");
return EXIT_SUCCESS;
}
What about
tempalte <int N1, int N2> class Test
{
public:
int iArray[N1][N2];
};
?
Test.What about putting a std::vector in a vector?
std::vector< std::vector< const int > > iArray;
There aren't many reason to use "plain" arrays in C++.
int[][] doesn't), and it has a separate allocation per line (which can also affect locality). Writing a simple matrix class based on std::vector<int> is not rocket science, however.If you want to decide int iArray[][]; size later then you can use vector< vector<int> > iArray;.
The other way is to use nested new[], which would be little complex.
No this is not possible. But you can have a pointer in your class like
int **ptr;
and then in the constructor or where ever allocate the memory for your array with
ptr = (int **)malloc( the size you want );
or with the "new[]"-operator in C++.
but if you are using C++ .. the best way is to use:
std::vector< std::vector< int >> array;
class Test
{
public:
Test()
{
iArray = new int*[5];
for(int i = 0; i < 5; i++)
iArray[i] = new int[4];
}
~Test()
{
for(int i = 0; i < 5; i++)
delete[] iArray[i];
delete[] iArray;
}
int** iArray;
};
Will allow you to allocate a 2d int array at runtime (in this example it is a 5x4), but in all honestly I would use vectors as pointed out by some other posters, you don't need to worry about freeing the memory afterwards like you do with the use of new.
error: declaration of iArray as multidimensional array must have bounds for all dimensions except the first- I think that explains it as well as I can.[]operator.