Labels

About Labels

Labels are used as markers throughout the program. Labels are used to mark a position in the program to 'jump to' from another position using a goto, gosub, or other command.

Labels can be any word (that is not already a reserved keyword) and may contain digits and the underscore character. Labels must start with a letter or underscore (not a digit), and are followed directly by a colon (:) at the marker position. The colon is not required within the actual commands.

The compiler is not case sensitive. Lower and/or upper case may be used at any time.

Example:

    'This program will flash the light until the button is pressed
    'off. Notice the label named SWITCH_OFF.

    #chip 16F628A, 4

    #define BUTTON PORTB.0
    #define LIGHT PORTB.1
    Dir BUTTON In
    Dir LIGHT Out

    Do
    PulseOut LIGHT, 500 ms
    If BUTTON = 1 Then Goto SWITCH_OFF          ' <<< jumping to a label
    Wait 500 ms
    If BUTTON = 1 Then Goto SWITCH_OFF
    Loop

    SWITCH_OFF:
    Set LIGHT Off
    'Chip will enter low power mode when program ends

Key line: If BUTTON = 1 Then Goto SWITCH_OFF — as soon as the button is read as pressed, execution jumps straight to the SWITCH_OFF: label below, skipping the rest of the loop body and turning the light off.

See Also:

  • Goto — unconditional jump to a label
  • Gosub — calling a label as a subroutine
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