Re: Lifetime of a temporary that is bound to a reference

From:
"Matthias Hofmann" <hofmann@anvil-soft.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Tue, 22 May 2007 06:19:51 CST
Message-ID:
<5bflinF2sf2spU1@mid.individual.net>
"Markus Schoder" <a3vr6dsg-usenet@yahoo.de> schrieb im Newsbeitrag
news:pan.2007.05.21.23.30.23@yahoo.de...

#include <iostream>

class Foo
{
     const int& m_value;

public:
     Foo( const int& value ) : m_value( value ) {} void f() { std::cout
     << m_value << std::endl; }
};

Foo x( 42 );

int main()
{
     // Output is "1" on VC++
     // 2005 Express Edition.
     x.f();
}


The lifetime of temporaries bound to a constructor's parameters lasts
until the initialisation is completed. So this example has undefined
behaviour.


Until the initialisation is complete? Does that mean that the following
example has undefined behaviour as well?

#include <iostream>

class Foo { /* same as before */ };

int main()
{
     Foo( 42 ).f();
}

Note that the call to Foo:f() occurs after the constructor has completed.

--
Matthias Hofmann
Anvil-Soft, CEO
http://www.anvil-soft.com - The Creators of Toilet Tycoon
http://www.anvil-soft.de - Die Macher des Klomanagers

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