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Full Discussion: A trivial XOR doubt in a program
Top Forums Programming A trivial XOR doubt in a program Post 302247330 by jim mcnamara on Wednesday 15th of October 2008 12:05:00 PM
Old 10-15-2008
The short answer - it is an undefined operation. Means that the C standard regards this as garbage, and your compiler was polite enough to produce spaces.
The reason: there are no sequence points in the line between important steps.

A ; character creates a sequence point. So the first version works. This means the compiler can do any of those calculations in any order...

By the way, that 'swap' algorithm in general is a bad idea; it has unsafe properties. You should use a temp variable. It may look cool to you, but that is about it.
 

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LEARN ABOUT CENTOS

uil

uil(user cmd)															     uil(user cmd)

NAME

       uil -- The user interface language compiler

SYNOPSIS

       uil [options ]  [file]

DESCRIPTION

       The uil command invokes the UIL compiler. The User Interface Language (UIL) is a specification language for describing the initial state of
       a user interface for a Motif application. The specification describes the objects (menus, dialog boxes, labels, push buttons,  and  so  on)
       used in the interface and specifies the routines to be called when the interface changes state as a result of user interaction.

       file	 Specifies the file to be compiled through the UIL compiler.

       options	 Specifies one or more of the following options:

		 -Ipathname
			   This option causes the compiler to look for include files in the directory specified if the include files have not been
			   found in the paths that already were searched.  Specify this option followed by a pathname, with no intervening spaces.

		 -m	   Machine code is listed. This directs the compiler to place in the listing file a description of  the  records  that	it
			   added to the User Interface Database (UID). This helps you isolate errors. The default is no machine code.

		 -o file

			   Directs  the  compiler  to  produce	a UID.	By default, UIL creates a UID with the name a.uid.  The file specifies the
			   filename for the UID.  No UID is produced if the compiler issues any diagnostics categorized as error or  severe.  UIDs
			   are portable only across same-size machine architectures.

		 -s	   Directs  the  compiler  to set the locale before compiling any files.  The locale is set in an implementation-dependent
			   manner.  On ANSI C-based systems, the locale is usually set by calling setlocale(LC_ALL, "").  If this  option  is  not
			   specified, the compiler does not set the locale.

		 -v file   Directs  the compiler to generate a listing.  The file specifies the filename for the listing.  If the -v option is not
			   present, no listing is generated by the compiler.  The default is no listing.

		 -w	   Specifies that the compiler suppress all warning and informational messages.  If this option is not present,  all  mes-
			   sages are generated, regardless of the severity.

		 -wmd file Specifies a binary widget meta-language description file to be used in place of the default WML description.

RELATED INFORMATION

       X(1) and Uil(3).

																     uil(user cmd)
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