Test whether or not a 4x4 matrix is a magic square
The size of the matrix is hard-coded all over the place.  You made a good attempt to define const int SIZE = 4 in main(), and you pass SIZE to your functions.  However, you still hard-code int matrix[][4], int row[4], and int column[4] in the function signatures.  In addition, fillMatrix() says "Enter four values for row ".

There are several possible remedies.


The simplest is to #define SIZE 4, and don't bother passing the size around anymore.  It's more of a C-style approach, but at least the size will be centrally defined.
You could store the matrix in a std::array&lt;std::array&lt;int&gt;&gt; (C++11), a std::vector&lt;std::vector&lt;int&gt;&gt;, or a std::valarray&lt;std::valarray&lt;int&gt;&gt;.  Then the helper functions could obtained the dimensions by calling .size().
You could flatten the matrix into a one-dimensional array, and pass the size.
You could define a Matrix class.