Write a function in c++ that takes as input parameters an array of characters and a length field. The function will create a square matrix from the array by first determining the largest square matrix that will hold as many numbers as possible yet not have any blank spaces. If the arrays length in 40 the square matrix would be 6 x 6, then create a square matrix where order matters

Then print the diagonal of the matrix.

Input:

['c', 'a', 't', 'd', 'o', 'g', 'f', 'i', 's', 'h', 'a'], 11

[[c, a, t ], [d, o, g] [f, i, s]]

output: cos