How to Determine the Current DO Nesting Level

• Microsoft Visual FoxPro for Windows, version 3.0
• Microsoft FoxPro for Windows, versions 2.5 and 2.5a
• Microsoft FoxPro for MS-DOS, versions 1.02, 2.0, 2.5, and 2.5a
• Microsoft FoxBASE+ for MS-DOS, version 2.01
• Microsoft FoxBASE+ for the Macintosh, version 2.01

SUMMARY

FoxBASE+ and FoxPro allow DO programs to be nested. The maximum number of nesting levels for FoxBASE+ is 24, while FoxPro allows a maximum of 32 levels and Visual FoxPro allows a maximum of 128 levels. Exceeding this limit results in error number 103, "DO nesting too deep."

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.

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