Is this code using casts valid in C++ ?

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2 total messages Started by Louis Lamarche Tue, 05 Feb 1991 00:39

#811

Author: Louis Lamarche
Date: Tue, 05 Feb 1991 00:39

17 lines
1037 bytes

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 ?

-- 
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| Louis Lamarche, IREQ |       lamarche@IREQ.Hydro.Qc.CA
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| QC, Canada, J3X 1S1  |  514-652-8077 (office)  514-324-2919 (home)

Re: Is this code using casts valid in C++ ?

#819

Author: Ron Guilmette
Date: Fri, 08 Feb 1991 06:07

23 lines
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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