INPUT.CHAR [Revelation On-Line Wiki]

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====== INPUT.CHAR ======

^Published By^Date^Version^Knowledge Level^Keywords^
|Revelation Technologies|14 NOV 1989|2.X|EXPERT|INPUT.CHAR, |

==== Description ====
 
INPUT.CHAR is the fundamental subroutine in  
Advanced Revelation for processing keyboard input.  INPUT.CHAR processes a single  
keystroke (or function key), returning only when a key is  
pressed.  All keystrokes are processed except those defined  
as priority interrupts in @PRIORITY.INT  
(see Appendix 1, System Variables).  User environment  
restrictions may also apply to certain keys.  These are  
defined in @ENVIRON.SET (see Appendix 1).   

INPUT.CHAR is also the basis for the indexing timeout loop, used to determine when  
background indexing is to occur. 

==== Arguments ====
 
=== key ===
 
An optional variable used by INPUT.CHAR to  
return the ASCII code for the keystroke entered by the user 

==== Values returned ====
 
If specified, key contains the ASCII coded  
keystroke.  This is a two-character ASCII sequence (the  
initial value is 0) if a function key is pressed. 

==== Examples ====

<code>
*Initialization 
DECLARE SUBROUTINE INPUT.CHAR,MSG 
 
*Display the ASCII code for the keystroke 
CHARACTER = '' 
IMAGE = '' 
MSG('Please enter a character:','UB',IMAGE,'') 
INPUT.CHAR(CHARACTER) 
IF LEN(CHARACTER) >> 1 THEN 
*The key pressed was a function key or function key sequence. 
CHAR1 = SEQ(CHARACTER[1,1]) 
CHAR2 = SEQ(CHARACTER[2,1]) 
CHARACTER = CHAR1:' ':CHAR2 
END ELSE 
CHARACTER = SEQ(CHARACTER) 
END 
MSG('The ASCII code for the keystroke entered is: %1%','','', CHARACTER) 
MSG('','DB',IMAGE,'')
</code>