Write a rudimentary spreadsheet program. Display a grid of cells with columns A through H and rows 1 through 20. Accept input in the first row of the screen. The commands are of the form column row...

Write a rudimentary spreadsheet program. Display a grid of cells with columns A through H and rows 1 through 20. Accept input in the first row of the screen. The commands are of the form column row entry, where entry is either a number, a cell address preceded by a plus (e.g., +A5), a string, or a function preceded by an at sign, @. The functions are: max, min, avg, and sum. During execution of your program, build and modify the graph reflecting the situation in the spreadsheet. Show the proper values in proper cells. If a value in a cell is updated, then the values in all cells depending on it should also be modified. For example, after the following sequence of entries:

     A1 10

     B1 20

     A2 30

     D1 +A1

     C1 @sum(A1..B2)

     D1 +C1

both cells C1 and D1 should display the number 60.

       Consider using a modification of the interpreter from Chapter 5 as an enhancement of this spreadsheet so that arithmetic expressions could also be used to enter values, such as

     C3 2*A1

     C4 @max(A1..B2) – (A2 + B2)