unsigned char j[4][4];
And I want pass this element to the constructor of a class, I have a attribute in the class with the same type as the matrix
class x{
private:
unsigned char x[4][4];
public:
x(unsigned char j[4][4]);
};
I put values in my matrix j and in the constructor I want equalize j and x like this
x(unsigned char j[4][4]){
x = j;
}
but and error appear in the code
incompatible types in assignment of ‘unsigned char (*)[4]’ to ‘unsigned char [4][4]’
why?
You cannot pass arrays as arguments like this. You should not be using arrays to begin with. Really, just don't. The problem you're facing is just one problem out of a multitude of problems you will have when using arrays.
Instead, use an std::array that contains another std::array (so that it's two-dimensional):
#include <array>
class X {
private:
std::array<std::array<unsigned char, 4>, 4> x;
public:
X(std::array<std::array<unsigned char, 4>, 4> j);
};
In your constructor, just assign:
X(std::array<std::array<unsigned char, 4>, 4> j)
{
x = j;
}
or, even better, use a constructor initialization list:
X(std::array<std::array<unsigned char, 4>, 4> j)
: x(j)
{ }
(Also note that I changed your class name from x to X (capital.) Don't use conflicting names for classes and variables. It's confusing :-)
If you need your matrix to have a size that's determined at runtime instead of having a fixed size, then use std::vector instead of std::array.
You can't just assign arrays to each other: they're no vectors, which you can assign safely.
You'll have to iterate over that array passed as a parameter and copy its contents:
for(size_t i = 0; i < 4; ++i)
for(size_t j = 0; j < 4; ++j)
this->x[i][j] = argument_called_j[i][j];
BTW, to my mind, this x variable is a bit confusing because there's a class called x. If you'd like to take a look at how one could build such a class to work with matrices, check out my project called Matrix on GitHub.
