How to pass an Array into a Class in C++ - c++

Question

When i create a class I would like to be able to store an array in that class. Is this possible?
For example. If i have a class called array to store an array from my main function
int main()
{
double nums[3] = {1 2 3}
array Vnums(nums)
return 0
}
class array
{
public
//constructor
array(double nums[])
{
double vector[] = nums;
}// end constructor
}// end array
Thank you!

Answer 1

use a std::array instead of a raw array. It's just like a raw array, but copiable, and has useful member functions.
class array
{
std::array<double, 3> classArray;
public:
//constructor
explicit array(const std::array<double, 3>& rhs)
:classArray(rhs)
{}// end constructor
}// end array
int main()
{
std::array<double, 3> nums = {{1 2 3}};
array Vnums(nums)
return 0
}
or maybe a std::vector if you want to be able to change the size at will
class array
{
std::vector<double> classArray;
public:
//constructor
explicit array(const std::vector<double>& rhs)
:classArray(rhs)
{}// end constructor
}// end array
int main()
{
std::vector<double> nums{1 2 3}; //C++11 feature
array Vnums(nums)
return 0
}
I'm not sure what you're doing, so it's hard to give solid advice. You can pass a raw array by reference, a pointer and a count, an iterator pair...

Answer 2

Yes, but you must either allocate the array dynamically upon class creation, or the array must always be the same size.
Option A:
class array{
private:
double* data;
unsigned size;
public:
array(double* d, unsigned s){
size = s;
data = new double[size];
for(unsigned i = 0; i < s; i++)
data[i]=d[i];
}
array(const array& copy){
double* temp = new double[copy.size];
delete [] data;
data = temp;
size = copy.size;
for(unsigned i = 0; i < size; i++)
temp[i]=copy.data[i];
}
array& operator= (const array& copy){
double* temp = new double[copy.size];
delete [] data;
data = temp;
size = copy.size;
for(unsigned i = 0; i < size; i++) data[i]=copy.data[i];
}
~array(){
delete[] data; // Don't forget the destructor!
}
};
This is probably the way you need, but note that you will almost certainly need the custom copy constructor and assignment operator so that you don't share any memory between multiple instances of this class. A better way might be to make a copy function that both can use.
Option B:
class array{
private:
double data[3];
public:
array(double* d){ //or "double(&d)[3]" to be safer, but less flexible
for(unsigned i = 0; i < 3; i++){
data[i] = d[i]; // If d is not at least size 3, your program will crash here (or later on, or maybe just act in an undefined way)
}
}
}
Haven't tested this, but it should be an ok starting point.