Logic Expression

Free Software for Developers

Using program


Analogous to arithmetic, there exists logical (Boolean) expressions. Those are expressions that are built using logical operators: negation '#', conjunction '*', disjunction '+', exclusive disjunction '!+', implication '=>' and equivalency '<=>', over the set of 2 (two) elements, where elements consist of 'False' and 'True', i.e. '0' and '1' respectively. Priorities of operators are given according to standard convention: the highest priority is by parenthesis '(' and ')' which have to be present in pair, followed by '#', '*', '+' and '!+', with '=>' and '<=>' having the least priority. Expression is calculated from left to the right.

Logical expression that conforms to the syntax rules is input in the field Editor of logical expression, labeled A, from tab Editor of the Main window. Available options are New (for creation of a new document) and Open (for opening of an existing document). When editing expression one can use standard procedures for Copying and Pasting of text. User can always save result of his work using options Save and Save As from the toolbar or main menu.

When the expression is formed, user have to click with mouse (CLICK ME!) in the Logical express field, marked with the letter C, where syntax check of the expression is done. If there is an error, Error dialogue is opened, and user is warned of the type of error and place where it appeared. This window is so called modal window which stops program until closed. After closing Error dialogue, user can fix an error. Procedure is repeated until program successfully verify syntax correctness of the logical expression.

Program displays verified logical expression in the field Logical expression, marked with the letter C, translated (meaning that to every mnemonic variable name from the field A is assigned symbol of English alphabet, i.e. symbolical name). At the same time, program displays a list of variables in the field List of variables, marked with B, which contains: assigned symbolical name from the field C and mnemonic variable name from the field A. Checking items of the list will assign value to that item (this is true for small variables). The expression is than ready for evaluation.

Click to the toolbar button Run! (or from the main menu) starts expression evaluation.

Values of the variables and evaluated result is displayed on the Result tab in the fields Header, marked with A, Variable list, marked with B, and Result, marked with C. Values of the variables and the result [R] is read as shown by arrows.

If there exists more big variables, i.e. there are a lot of results, finding particular values of variables and result is done through Find dialogue.

Using program LE is very simple. The easiest way is by using toolbar.

Some parameters, important for program, can be read on the bottom of main window - on status line.



Status line