Article View: comp.std.c++
Article #819Re: Is this code using casts valid in C++ ?
From: Ron Guilmette
Date: Fri, 08 Feb 1991 06:07
Date: Fri, 08 Feb 1991 06:07
23 lines
1179 bytes
1179 bytes
In article <5217@s3.ireq.hydro.qc.ca> lamarche@ireq.hydro.qc.ca (Louis Lamarche) writes:
+class foo { int a; };
+class foob : public foo { int b; };
+foo afoo;
+foo* afooPtr = &afoo;
+foob* afoobPtr = (foob*) afooPtr;
+foo& afooRef = afoo;
+foob& afoobRef = (foob&) afooRef; // Ok with g++1.37.0, rejected by g++1.37.2-
+main(){}
+
+This code compiles well with CC 2.0 on a Sun and with Zortech 2.1, but fails
+with g++1.37.2-. Is it legal ?
No. That's illegal.
In your example, a `foob' is a `foo' but not vise-versa. Thus, you may
convert a `foob&' to a `foo&' but not vise-versa.
--
// Ron Guilmette - C++ Entomologist
// Internet: rfg@ncd.com uucp: ...uunet!lupine!rfg
// Motto: If it sticks, force it. If it breaks, it needed replacing anyway.
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!decwrl!infopiz!lupine!rfg From: rfg@NCD.COM (Ron Guilmette) Newsgroups: comp.std.c++ Subject: Re: Is this code using casts valid in C++ ? Message-ID: <3789@lupine.NCD.COM> Date: 8 Feb 91 06:07:52 GMT References: <5217@s3.ireq.hydro.qc.ca> Organization: Network Computing Devices, Inc., Mt. View, CA Lines: 23