Using Flags

You can use flags to control calculator behavior and program execution. You can think of a flag as a switch that is either on (set) or off (clear). You can test a flag’s state within a conditional or loop structure to make a decision. Because certain flags have unique meanings for the calculator, flag tests expand a program’s decision-making capabilities beyond that available with comparison and logical functions.

Types of Flags

The calculator has two types of flags:

System flags. Flags –1 through –128. These flags have predefined meanings for the calculator.

User flags. Flags 1 through 128. User flags are, for the most part, not used by any built-in operations. What they mean depends entirely on how the program uses them.

Appendix C lists the 128 system flags and their definitions. For example, system flag –40 controls the clock display

—when this flag is clear (the default state), the clock is not displayed — when this flag is set, the clock is displayed. (When you press %CLK% in the H%MISC% menu, you are setting or clearing flag –40.)

Note that for these calculators, there are no display annunciators to indicate that user flags 1 through 5 are set, like the older HP 48S-series and HP 48G-series calculators.

Setting, Clearing, and Testing Flags

Flag commands take a flag number from the stack — an integer 1 through 128 (for user flags) or –1 through –128 (for system flags).

To set, clear, or test a flag:

1.Enter the flag number (positive or negative).

2.Execute the flag command — see the table below.

Flag Commands

Key

Programmable

Description

 

Command

 

 

 

 

!°%TEST% LL:

 

 

 

 

%SF%

SF

Sets the flag.

%CF%

CF

Clears the flag.

%FS?%

FS?

Returns 1. (true) if the flag is set, or

 

 

0. (false) if the flag is clear.

%FC?%

FC?

Returns 1. (true) if the flag is clear,

 

 

or 0. (false) if the flag is set.

%FS?C%

FS?C

Tests the flag (returns true if the

 

 

flag is set), then clears the flag.

%FC?C%

FC?C

Tests the flag (returns true if the

 

 

flag is clear), then clears the flag.

 

 

 

RPL Programming 1-27