?

The question sign is one of the most useful commands in ASSIST. It accepts any expressions and evaluates them according to dBASE rules. For example:

• Type in: 12 (without quotes).You will get an answer: 12 (because 12 = 12).
• Type in: "12" (in quotes). You will also get an answer: 12 (the computer evaluates any sequence of enquoted symbols as a character constant expression).
• Type in: 12/4. You will get an answer: 3 (because 12/4 = 3). This is useful because you can use the ? sign as a calculator for all types of mathematical expressions (see below on their syntax rules).
• Type in: "12/4". This time the computer understands it as a symbolic constant and gives a response: 12/4.
• Type in: GREETING (without quotes). You will get an answer: Unknown variable! - because the computer evaluates any character string without quotes as a name of a certain memory variable, but it can not in this case find a variable called GREETING. However, if you had previously assigned the string "Hello!" to the variable GREETING (using the assignment operator: GREETING := "Hello!" ), the computer will find it and answer: Hello!.
• Type in: 2*2=4. You will get an answer: Y (because it's true).
• Type in: 2*2=5. You will get an answer: N (because it's false).

"Y" and "N" stand for special dBASE logical expressions .T. and .F. (denoted by two dots; about other expressions of this type see below).

• Open aand.dbf (in Edit or Browse), go to record 4 and after choosing the ? command type in: WORD (without quotes). You will get the answer: ashes. The computer interprets field names of an open file as memory variables and demonstrates to you their current values.
• Type in: TIME() (this way - with round brackets after TIME). You will be told the current time (if there is a clock driver installed in your machine).

The last examples demonstrates the use of a dBASE function as an expression. You can use any valid dBASE expressions as input to the ? commands (and some others, too - see below). So now we will pass on to the important question of the structure of dBASE expressions. You will find much of this information very useful (if you are not yet acquainted with dBASE) because it can help you in lots of file operations (LOCATing/SEEKing, INDEXing, SORTing, LISTing etc.).

One more remark about the ? command. Star4Win, like StarLing, has a built-in interpreter. You may write a .prg file and execute it by typing: "DO name of the .prg" in the ? window. However, the syntax of the built-in interpreter is somewhat different from the standard DBase language. This, and a great number of new functions and procedures available for use is covered in other Help sections. For details about the interpreter, see STAR4WIN PROGRAM INTERPRETER.

The ? window can also be used to run external executable files; to enter a DOS command you can type "DOS " followed by the command name (e.g. DOS dir).

In Star4Win you can also call internal procedures (such as NOTEFIELD, COMPOSE etc.) as functions using the ASSIST ? option. It means that entering COMPOSE() in the ? window will have the same results as running the COMPOSE procedure from the Procedures option of the main menu.

See also: Syntax of xBase expressions, Standard xBase functions, StarLing / Star4Win functions.

[Compatibility: The StarLing clauses PRINT ON/OFF, DECIMALS ON/OFF are not supported in Star4Win].