PICBASIC PLUS LITE Manual - Profe Saul

PICBASIC PLUS CompilerThe ELSE is optional. If it is missed out then if the expression is falsethe program continues after the ENDIF line.Example 2 :IF X & 1 = 0 THENA = 0B = 1ELSEA = 1ENDIFIF Z = 1 THENA = 0B = 0ENDIFA third form of IF, allows the ELSE to be placed on the same line asthe IF: -IF X >= 10 THEN HIGH LED1 : ELSE LOW LED2Notice that there is no ENDIF instruction. The comparison is automaticallyterminated by the end of line condition. So in the above example,if X is greater or equal to 10 then LED1 will illuminate, otherwise,LED2 will illuminate.The IF statement allows any type of variable, register or constant tobe compared. A common use for this is checking a Port bit: -IF PORTA.0 = 1 THEN HIGH LED: ELSE LOW LEDAny commands on the same line after THEN will only be executed ifthe comparison if fulfilled: -IF VAR = 1 THEN HIGH LED : DELAYMS 500 : LOW LEDNotes : A GOTO command is optional after the THEN: -IF PORTB.0 = 1 THEN LABELIn fact, the THEN is also optional, however code is more understandablewith the THEN in place. Consider the following two lines of code.IF VAR = 1 THEN VAR = 10andIF VAR = 1 VAR = 10Both lines produce the same result, but the second line is a bit easierto understand. The decision is yours to make whether to use theTHEN part of the constructor not.66Copyright Crownhill 2001