ON ... GOSUB, ON ... GOTO, ON ... CALL statement

Purpose: These are control flow statements that will branch to a line label or subroutine depending on the value of a number.


Syntax 1: 

 ON Number GOSUB List
Syntax 2: 

 ON Number GOTO List
Syntax 3: 

 ON Number CALL List

Parameters:

  • Data type: INTEGER
    Number Integer literal or variable that corresponds to the position in the list of the label or subroutine name. The value of Number determines to which label or subroutine in the list the program branches.For example, if the value is 2, the label specified in the second position in the list is the destination of the branch.
  • Data type: Identifier
    List Comma separated list of labels or subroutine names.

Example 1: 


 GLOBAL i
 INPUT "Enter one number, 1, 2, or 3. " , i

 ON i CALL   Sub_one, Sub_two, Sub_three
 ON i GOSUB One, Two, Three
 ON i GOTO  Label_One, Label_Two, Label_Three

 END ' To stop the program from flowing to the code below

 Label_One:
 PRINT "Label One"
 END

 Label_Two:
 PRINT "Label Two"
 END

 Label_Three:
 PRINT "Label Three"
 END

 One:
 PRINT "Subroutine One"
 RETURN

 Two:
 PRINT "Subroutine Two"
 RETURN

 Three:
 PRINT "Subroutine Three"
 RETURN

 SUB  Sub_one
  PRINT "SUB One"
 END SUB

 SUB  Sub_two
  PRINT "SUB Two"
 END SUB

 SUB  Sub_three
  PRINT "SUB Three"
 END SUB

Result: 


 Enter one number, 1, 2, or 3. 3
 SUB Three
 Subroutine Three
 Label Three

Example 2: 


 GUI "TestApp"
 
 SUB FORMLOAD
  GLOBAL Form1 AS CONTROL
  Form1 = BCX_FORM("Test Application")
  BCX_BUTTON("Test button #1", Form1, 201, 10, 10) ' <<<<< Ctrl = 201 
  BCX_BUTTON("Test button #2", Form1, 202, 10, 60) ' <<<<< Ctrl = 202 
  BCX_BUTTON("Test button #3", Form1, 203, 10, 110) ' <<<<< Ctrl = 203 
  CENTER(Form1)
  SHOW(Form1)
 END SUB
 
 BEGIN EVENTS
  SELECT CASE CBMSG
  CASE WM_COMMAND
   IF CBCTLMSG = BN_CLICKED THEN
    '******************************************************* 
    DIM RAW i = CBCTL-200 '<<< ctrl 201,202,203 ->> 1,2,3 
    ON i CALL OnClick1(i), OnClick2(i), OnClick3(i)
    '******************************************************* 
   END IF
  END SELECT
 END EVENTS
 
 SUB OnClick1(a) '<< Shows using a parameter 
  MSGBOX("Hello from click" + STR$(a))
 END SUB
 
 SUB OnClick2(a) '<< Shows using a parameter 
  MSGBOX("Hello from click" + STR$(a))
 END SUB
 
 SUB OnClick3(a) '<< Shows using a parameter 
  MSGBOX("Hello from click" + STR$(a))
 END SUB

BCX Console Sample Programs using ON ... GOSUB, ON ... GOTO, ON ... CALL function.

S134.bas