C++ Windows Programming

Source and target sets

Each cell in the spreadsheet holds a numerical value, a formula, or a (possibly empty) plain text. As mentioned at the beginning of the chapter, a formula is a text beginning with the equal sign (=) followed by a numerical expression with cell references. If the cell holds a value, it may affect the values in other cells (if it does not hold a value, it might cause evaluation errors in target cells). If the cell contains a formula, its value may depend on the values in other cells. This implies that each cell needs a set of cells that it depends on, that is, its source set, and a set of cells that depend on it, that is, its target set.

Only a formula has a non-empty source set, which is the set of all references of the formula. ...