Using multiple IF statements in a batch file

Question

When using more than 1 IF statement  is there a special guideline that should be followed  Should they be grouped  Should I use parenthesis to wrap the command s    An example to use would be   IF EXIST somefile txt IF EXIST someotherfile txt SET var somefile txt someotherfile txt

User · Answer

IF EXIST  somefile txt      IF EXIST  someotherfile txt        SET var  somefile txt   someotherfile txt        ELSE     CALL  SUB    SUB ECHO Sorry    nothin  there  GOTO EOF   Is this feasible   SETLOCAL ENABLEDELAYEDEXPANSION IF EXIST  somefile txt      SET var  somefile txt    IF EXIST  someotherfile txt        SET var  var   someotherfile txt        ELSE     IF EXIST  someotherfile txt        SET var  someotherfile txt      ELSE     GOTO EOF

User · Answer

Batch files have really very limited logic powers so the best you can hope to come up with is a good workaround that indirectly achieves what you want   That s not to say that you should feel they are inferior to a real language - they still demand the same attention to detail and manual debugging as a real application   It s just that you ll need to work a lot harder to make them do what you want in a robust manner   For the OP s question it sounds like you require two specific files to exist   Just use a tally   IF EXIST somefile txt       set  a file1 status 1    IF EXIST someotehrfile txt       set  a file2 status 1    set  a file status result file1 status   file2 status  if  file status result  equ 2       goto somefileexists    goto exit   somefileexists IF EXIST someotherfile txt SET var       exit   My example uses 3 variables  but you could just add 1 to file result status if the file exists   But if you want more granular control later in your batch file you can record the result for each file as I have done so you don t have to keep checking if a file exists later on

User · Answer

is there a special guideline that should be followed   There is no  standard  way to do batch files  because the vast majority of their authors and maintainers either don t understand programming concepts  or they think they don t apply to batch files   But I am a programmer   I m used to compiling  and I m used to debuggers   Batch files aren t compiled  and you can t run them through a debugger  so they make me nervous   I suggest you be extra strict on what you write  so you can be very sure it will do what you think it does   There are some coding standards that say  If you write an if statement  you must use braces  even if you don t have an else clause   This saves you from subtle  hard-to-debug problems  and is unambiguously readable   I see no reason you couldn t apply this reasoning to batch files   Let s take a look at your code   IF EXIST somefile txt IF EXIST someotherfile txt SET var somefile txt someotherfile txt   And the IF syntax  from the command  HELP IF   IF  NOT  ERRORLEVEL number command IF  NOT  string1  string2 command IF  NOT  EXISTS filename command       IF EXIST filename     command   ELSE     other command     So you are chaining IF s as commands   If you use the common coding-standard rule I mentioned above  you would always want to use parens   Here is how you would do so for your example code   IF EXIST  somefile txt      IF EXIST  someotherfile txt        SET var  somefile txt someotherfile txt          Make sure you cleanly format  and do some form of indentation   You do it in code  and you should do it in your batch scripts   Also  you should also get in the habit of always quoting your file names  and getting the quoting right   There is some verbiage under HELP FOR and HELP SET that will help you with removing extra quotes when re-quoting strings   Edit  From your comments  and re-reading your original question  it seems like you want to build a comma separated list of files that exist   For this case  you could simply use a bunch of if else statements  but that would result in a bunch of duplicated logic  and would not be at all clean if you had more than two files   A better way is to write a sub-routine that checks for a single file s existence  and appends to a variable if the file specified exists   Then just call that subroutine for each file you want to check for    ECHO OFF SETLOCAL  REM Todo  Set global script variables here CALL  MainScript GOTO  EOF  REM MainScript    MainScript   SETLOCAL    CALL  AddIfExists  somefile txt    files    files    CALL  AddIfExists  someotherfile txt    files    files     ECHO Files   files     ENDLOCAL GOTO  EOF  REM AddIfExists filename  existingFilenames  returnVariableName   AddIfExists   SETLOCAL    IF EXIST    1        SET  result   1      ELSE       SET  result                REM Cleanup  and return result - concatenate if necessary     ENDLOCAL      IF    2              SET    3  result         ELSE         SET    3   2  result             GOTO  EOF

User · Answer

The explanation given by Merlyn above is pretty complete  However  I would like to elaborate on coding standards   When several IF s are chained  the final command is executed when all the previous conditions are meet  this is equivalent to an AND operator  I used this behavior now and then  but I clearly indicate what I intend to do via an auxiliary Batch variable called AND   SET AND IF  IF EXIST somefile txt  AND  EXIST someotherfile txt SET var somefile txt someotherfile txt   Of course  this is NOT a true And operator and must not be used in combination with ELSE clause  This is just a programmer aid to increase the legibility of an instruction that is rarely used   When I write Batch programs I always use several auxiliary variables that I designed with the sole purpose of write more readable code  For example   SET AND IF SET THEN   SET ELSE   ELSE   SET NOELSE  SET ENDIF   SET BEGIN   SET END   SET RETURN EXIT  B   These variables aids in writting Batch programs in a much clearer way and helps to avoid subtle errors  as Merlyn suggested  For example   IF EXIST  somefile txt   THEN    IF EXIST  someotherfile txt   THEN      SET var  somefile txt someotherfile txt     NOELSE     ENDIF   NOELSE   ENDIF   IF EXIST    1   THEN    SET  result   1   ELSE    SET  result    ENDIF    I even have variables that aids in writting WHILE-DO and REPEAT-UNTIL like constructs  This means that Batch variables may be used in some degree as preprocessor values

User · Answer

You can structurize your batch file by using goto  IF EXIST somefile txt goto somefileexists goto exit   somefileexists IF EXIST someotherfile txt SET var       exit

[batch-file] Using multiple IF statements in a batch file

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