Q39585: Correct Testing Precedence of Batch File ERRORLEVELs

Article: Q39585
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:2.x,3.x,4.x,5.x,6.0,6.2,6.21,6.22
Operating System(s): 
Keyword(s): 
Last Modified: 17-DEC-2000

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The information in this article applies to:

- Microsoft MS-DOS operating system versions 2.11, 3.1, 3.2, 3.21, 3.3, 3.3a, 4.0, 4.01, 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
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SUMMARY
=======

When you use multiple IF ERRORLEVEL statements in batch files, the order in
which the ERRORLEVELs are tested numerically is important. The correct order is
descending (highest to lowest). This ordering is from the way ERRORLEVELs are
tested. The IF condition is set to TRUE when the ERRORLEVEL is equal to, or
greater than, the ERRORLEVEL number.

MORE INFORMATION
================

The following batch file fragment demonstrates this INCORRECT behavior:

     rem (execute a program which returns an errorlevel of 0 or 1)
     if errorlevel 0 goto ZERO
     if errorlevel 1 goto ONE
     goto END
     :ZERO
       echo a Zero was returned!
       goto END
     :ONE
       echo a One was returned!
     :END

The above example always branches to the "ZERO" label, regardless of success or
failure. This example would work correctly if the ERRORLEVEL testing was made in
descending order.

The CORRECT way to write such a batch file is as follows:

     rem (execute a program which returns an errorlevel of 0 or 1)
     if errorlevel 1 goto ONE
     if errorlevel 0 goto ZERO
     goto END
     :ZERO
       echo a Zero was returned!
       goto END
     :ONE
       echo a One was returned!
     :END

Additional query words: 6.22 2.x 3.x 4.00 4.01 5.00 5.00a 6.00 6.20 \* yeswin4

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Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS321 kbMSDOS400 kbMSDOS320 kbMSDOS330a kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS310 kbMSDOS500 kbMSDOS330 kbMSDOS401 kbMSDOS500a kbMSDOS211
Version           : MS-DOS:2.x,3.x,4.x,5.x,6.0,6.2,6.21,6.22

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