I don't think that technique is going to work, and would take quite a long time. What you need to do instead is have some kind of logic test based on the way the pieces move.

So for example, let's take the bishop. Each square would have to be identified by the row and column it is in. Number the columns 0 - 7 (or 1 - 8 if you like) from left to right, and the rows 0 - 7 (or 1 - 8) from top to bottom. So the top left square is 0,0, and the bottom right square is 7,7.

Then, the user attempts to make a move. You would have some function, let's call it Is_Move_Legal, that would first determine which type of piece is trying to move, then determine if the move was legal for that piece. It determines the piece is a bishop. The logic test for a bishop would be something like

if(abs(initial_row-final_row)=abs(initial_column-final_column), true, false)

What's happening here? You're basically determining how many columns the bishop moved (by subtracting the initial from the final and then taking the absolute value of that), and how many rows it moved (same process). A bishop moves diagonally. So, on any legal move, it will move an equal number of rows as columns, and the reverse is true: if the bishop moves an equal number of rows as columns, the move is legal.

Note that the "row" and "column" values would likely be assigned to the squares as opposed to the pieces. The "squares" will have to exist in your code for display purposes anyway, so you may as well use them in your game code. So the above logic test for a bishop would be retrieving those values from the squares that the bishop started and is attempting to end on.

Now, remember. You also need your function to check to see if the bishop illegally jumped over an enemy or friendly piece, is illegally trying to occupy the same square as a friendly piece, or if the move would illegally put or leave the user's king in check. But in terms of a piece's moving pattern, I think the above is the best method. Your method would require a different list of legal moves for each square that the piece may occupy.

Finally, note that I've only ever taken one computer science class, and it was a number of years ago, in Java. So there may be more elegant/simple solutions available that I don't know of.

-edited for spelling-