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Full Discussion: C++ Bug probably scope problem
Top Forums Programming C++ Bug probably scope problem Post 302914959 by Corona688 on Friday 29th of August 2014 11:36:09 AM
Old 08-29-2014
You have a big long cout calling multiple things which have side-effects on each other, and the order they are done is ambiguous -- remember this is a compiled, heavily optimized language, not a one-at-a-time string interpreter. Re-imagine your code like this:

myfunction(die1.getnum(), die2.getnum(), die1.roll(), die2.roll());

When written that way, whether roll() gets called before or after getnum() is more obviously ambiguous.

Split it into two cout statements to avoid the side-effects.

It has nothing to do with the const. It just means that calling that function has no side-effects. It doesn't guarantee that all other functions have no side effects however.
Last edited by Corona688; 08-29-2014 at 12:49 PM..
This User Gave Thanks to Corona688 For This Post:
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LEARN ABOUT OPENSOLARIS

getwc

getwc(3C)						   Standard C Library Functions 						 getwc(3C)

NAME

       getwc - get wide character from a stream

SYNOPSIS

       #include <stdio.h>
       #include <wchar.h>

       wint_t getwc(FILE *stream);

DESCRIPTION

       The getwc() function is equivalent to fgetwc(3C), except that if it is implemented as a macro it may evaluate stream more than once, so the
       argument should never be an expression with side effects.

RETURN VALUES

       Refer to fgetwc(3C).

ERRORS

       Refer to fgetwc(3C).

USAGE

       This interface is provided to align with some current implementations and with possible future ISO standards.

       Because it may be implemented as a macro, getwc() may treat incorrectly a stream argument with side effects.   In  particular,  getwc(*f++)
       may not work as expected.  Therefore, use of this function is not recommended; fgetwc(3C) should be used instead.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |ATTRIBUTE TYPE		     |ATTRIBUTE VALUE		   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       fgetwc(3C), attributes(5), standards(5)

SunOS 5.11							    24 Jul 2002 							 getwc(3C)
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