How to Determine the Current DO Nesting Level

MORE INFORMATION

DO levels are incremented as follows:

1. When a DO program1 command is issued in the Command window, the DO level is set to 1.
2. If program1 includes a DO program2 statement, the DO level is incremented to 2. The DO level is incremented each time another DO program statement is executed. In this scenario, program1 would be referred to as the calling program, and program2 as the called called program.
3. If a called program returns to a calling program, either by executing all commands in the called program, or by explicitly issuing a RETURN command, the DO level is decremented by 1.

The following procedure allows you to determine the current DO level through use of the SYS(16) function. The SYS(16) function returns the name of the currently executing program. It also allows an optional numeric argument that indicates from how many levels back the program name should be fetched.

1. Create a program named DOLVL.PRG with the following commands:

         * Memory variable used:
         * current - name of currently executing program
         * do_ctr - counter which indicates current do level
   
         current = SYS(16)
         do_ctr = 1
         DO WHILE .T.
            IF SYS(16,do_ctr) <> current
               do_ctr = do_ctr + 1
             ELSE
                * In FoxBASE+ or FoxPro 1.02, remove the word WINDOW
                * in the following command
                WAIT WINDOW "Current DO level is " + STR(do_ctr,1,0)
                EXIT
             ENDIF
         ENDDO

2. Save and execute the program. A message will be displayed as follows:

   Current DO level is 1

3. Create a program named TEST.PRG with the following command and execute the program:

   DO dolvl.prg

4. A message will be displayed as follows:

   Current DO level is 2