More on setting Variables and Constants

Explanation

Within GCBASIC you can use regular variable assignments. But, you can also use C like maths assignments.

The following methods are also supported.

    GLCDPrintLoc += 6
    CharCode -= 15
    CharCode++
    CharCode---          ' <<< the decrement operator

Key line: CharCode--- — decrements CharCode by 1. GCBASIC uses three dashes here, not two, because -- inside an expression already means double-negation (equivalent to +); the extra dash disambiguates the decrement statement from that expression rule.

Within GCBASIC you can define binary, hexidecimal and decimal constants, see Constants. Please note what is and what is not support with respect to assigning numbers to constants. An example program examines what is supported. 

    #chip 16F88, 4
    #config Osc = MCLRE_OFF

    ' All these work
    #define Test1 0b11111111
    #define Test2 0B11111111
    #define Test3 255
    #define Test4 0xFF
    #define Test5 0xff
    #define Test6 0Xff

    # Proof - select each option one in turn
    dir porta Out

    porta = test1          ' <<< all six constants below resolve to the same value, 255
    porta = test2
    porta = test3
    porta = test4
    porta = test5
    porta = test6

Key line: porta = test1 — all six lines assign the identical value, 255, to porta; Test1/Test2 show that binary literals accept either case of b prefix, and Test4/Test5/Test6 show the same for hexadecimal, confirming GCBASIC’s numeric literal prefixes are case-insensitive.

You can assigned values/numbers with all the methods shown above (for constants and variables) but please be aware that you must Use '0' not '00'. One zero equates to zero and two zeros will give you an unassigned variable.

Constants:

A few critical constants are defined within GCBASIC , you can re-use these constants. They include:

    #define ON 1       ' These are defined in System.h
    #define OFF 0
    #define TRUE 255
    #define FALSE 0

    #define OSC = 1    ' These are defined in TIMER.H
    #define EXT = 2    ' and, are used by InitTimer0 command
    #define EXTOSC = 3

See Also:

  • Constants
  • Setting Variables — the assignment and calculation rules these shorthand operators build on
  • InitTimer0 — using the OSC/EXT/EXTOSC clock source constants shown above
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