There is a single table made up of table cells.
Each table cell is either empty or contains text or an expression to calculate its value.
Cells are addressed by row and column number, with an expression of the type RxCy , where x and y specify the row and column of the addressed cell, respectively.
Cell addressing can be absolute or relative:
- in absolute addressing, rows and columns are counted from the upper left corner of the table;
- with relative addressing, rows and columns are counted from the cell in which the relative addressing expression occurs. Relative addressing is specified when, in an R[x]C[y] expression, row or column numbers are enclosed in square brackets.
Text cells contain arbitrary text enclosed in quotation marks.
Expressions in cells are arithmetic expressions with operators +,-,*,/ and arguments integers or addresses of other cells.
The expression in each cell sets its value and is recalculated when any of the cells addressed in it changes its value.
In formulas, you can also use the following functions: if, and, not, or, as well as the Boolean operators ==, !=, <, > with their natural semantics.
Expressions can be of arbitrary complexity using parentheses and the semantics are as in C++.
The semantics of if are like the ?: operator in C++.
The table must support sum and count functions with two arguments - cell addresses.
These addresses define the corners of a rectangular area of the table that the functions must operate on.
The sum function finds the sum of the values of those cells, while count finds the number of non-empty cells.
The values of empty cells in this case are assumed to be 0. If the content of a text cell can be interpreted as a number (whole or fractional), then this is its value. Otherwise, the value is 0.
The system must support the following commands entered by the user in interactive mode:
| Command | Description |
|---|---|
| SET address expression | changes the value of the cell with the corresponding address |
| PRINT VAL address | prints the value of the cell with the corresponding address |
| PRINT EXPR address | prints the formula in the cell with the corresponding address |
| PRINT VAL ALL | prints the values of all cells in the table formatted, with cells in a single row printed on a single line on the screen (*) |
| PRINT EXPR ALL | prints the formulas of all cells in the table formatted, with cells in a single row printed on a single line on the screen (*) |
| SAVE file | saves the contents of the table (as formulas) to a .csv file |
| LOAD file | reads table contents (as formulas) from a .csv file |
| ++ address | if the expression at the corresponding address is an integer, increments it by one |
| -- address | if the expression at the corresponding address is an integer, decrements it by one |
(*)If the screen width is not enough for all the cells of the rows, the table is divided into sub-tables and they are printed one by one.