Microsoft KB Archive/99067

= REXX Practices, Peculiarities and Problems =

Article ID: 99067

Article Last Modified on 10/31/2006



This article was previously published under Q99067



SUMMARY
This article discusses known peculiarities and problems with OS/2 version 1.31 REXX.



MORE INFORMATION
DISCLAIMER: This article is provided for users capable of developing programs with the information presented; it is not an extensive treatment of the language but rather a quick reference to aid someone in writing simple routines. Microsoft cannot support programming efforts beyond reproducing and submitting problems with the language implementation itself. If you need further assistance, consult REXX references such as &quot;The REXX Language, A Practical Approach to Programming&quot; by M. F. Cowlishaw, Prentice-Hall, Englewood Cliffs, 1985.

REXX files do NOT accept batch file labels; therefore, the GOTO command is unusable. Use the SIGNAL, LEAVE, or ITERATE instructions (see further below). A REXX label has a colon appended (rather than prepended) to it.

There can be no spaces between a function call and its parentheses. For example, MAX (5,7) is not valid. It must be MAX(5,7).

Multiple arguments in call statements are concatenated together to form one argument. Each argument needs to be separated by a space and can be extracted in the subroutine with a &quot;PARSE ARG var1 var2 ... var?&quot; style command. In function calls, multiple parameters separated by commas can accessed with &quot;PARSE ARG var1, var2 ...&quot;. Note that the commas are not enclosed in quotation marks as might be expected.

Parameters to commands specified in REXX may need to be enclosed in quotation marks. For example, DIRECTORY(c:\public) produces an error. DIRECTORY(&quot;c:\public&quot;) is the correct form of the command.

Anything not recognized by REXX as a syntax error or one of its own keywords is considered to be a command to be executed by OS/2. Watch out for intended REXX statements being evaluated as commands; for example, if longstr = abcdefghi then the intended REXX statement (which is explained later) substr(longstr,2,5) produces

bcdef

which REXX doesn't recognize and therefore tries to execute as a command. Unless a program or batch file named &quot;bcdef&quot; exists in the path, this produces an error. The appropriate way to accomplish the above is: var = substr(longstr,2,5) It is best to put any complex strings used by REXX in quotation marks so that REXX keywords accidentally embedded in the text don't produce errors.

When a command such as &quot;copy a:*.* b:&quot; is executed in REXX, the system variable &quot;rc&quot; holds the return code from the command. Usually a zero return code means success and non-zero code means failure. To get a return code in REXX without having a message appear on the screen and prompt for a response, use the AUTOFAIL=YES command in CONFIG.SYS.

CTRL+BREAK or CTRL+BREAK followed by ENTER breaks out of most REXX programming. The ENTER may be needed depending on the programming code context when the CTRL+BREAK was pressed.

Help on REXX error messages can be obtained at the command prompt by typing help rexnnnn. Note that, in this case, there is only one X in the message number prefix instead of the two in the language name. If you want to try a single REXX command or even a few commands, use the REXXTRY program. The syntax for the command is: REXXTRY rexx_command1;rexx_command2;rexx_command3 ... Note that semicolons separate each command. Also note that any action you take with REXXTRY is the same as if you had run it in a REXX program. For example, if you delete a file using REXXTRY, then the file is gone.

In addition to REXXTRY, there is PMREXX, which is a Presentation Manager interface you can use to run REXX programs. The syntax is: PMREXX rexx_file.cmd Not using the &quot;b&quot; (binary) suffix on strings supplied to BITAND or BITOR or BITXOR causes these functions to consider them to be character strings, resulting in the bit operation being applied to all bits of all characters in the strings.

Using the REXX FORMAT command, if you specify an exponential trigger and an integer size where the trigger is greater than the size of the integer part, the results are not always consistent. For example, if you have FORMAT(123456,2,2,2,3), it should theoretically (and sometimes does) work. This is because the exponent trigger of 3 combined with a six-digit number should trigger exponential format. This would produce one integral digit that is less than the two specified in the FORMAT command. Unfortunately, under some circumstances, a REXX error is produced. Avoid this situation by supplying an exponential trigger that is not greater than the integer value.

Additional query words: 2.10 2.1 2.10a 2.1a 2.20 2.2

Keywords: KB99067

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