Problem with an array in C#. How to print an array?

Question

Hello,
first i have a variable set to #.
string a = “#“;
Than I have an string array with some variables inside:
string [,] name = new string [,] { {“_“}, {a}};
Later in this code, i set the variable a to “O“.
At the end i print the array name with foreach.
But always, where the variable a is, there is # printed for the variable instead of O.

I dont understand why it doesn't work.
I hope you understood my problem and can help me.