C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  C program is standard C++ program? Goto page 1, 2, 3, 4  Next          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message strutsng@gmail.com Guest Posted: Sat Oct 22, 2005 7:58 am    Post subject: C program is standard C++ program? I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? In a C++ program, we can use standard C libraries. However, we cannot use C++ libraries inside C program. Please advise. thanks!! Back to top Jonathan Mcdougall Guest Posted: Sat Oct 22, 2005 8:16 am    Post subject: Re: C program is standard C++ program? [email]strutsng (AT) gmail (DOT) com[/email] wrote: Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? No. void template() { } int main() { template(); } is a valid C, but invalid C++. Check your favorite textbook (you do have one, don't you?) or google for more informations on C and C++ incompatibilities. Quote: In a C++ program, we can use standard C libraries. However, we cannot use C++ libraries inside C program. It depends on what you call a "C++ library". extern "C" { void f(); } Is this a "C++ library"? If yes, then a C program can use some C++ libraries. Your question is too vague. Jonathan Back to top Marcus Kwok Guest Posted: Sat Oct 22, 2005 8:22 am    Post subject: Re: C program is standard C++ program? In comp.lang.c++ [email]strutsng (AT) gmail (DOT) com[/email] wrote: Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? In most cases, yes, but there are a few cases where this is not true. For example, if a C program declares identifiers that are now C++ keywords but that are not C keywords. TC++PL has a section on this topic. Quote: In a C++ program, we can use standard C libraries. However, we cannot use C++ libraries inside C program. True. -- Marcus Kwok Back to top Marcus Kwok Guest Posted: Sat Oct 22, 2005 8:24 am    Post subject: Re: C program is standard C++ program? Quote: In comp.lang.c++ [email]strutsng (AT) gmail (DOT) com[/email] wrote: In a C++ program, we can use standard C libraries. However, we cannot use C++ libraries inside C program. In comp.lang.c++ Marcus Kwok <ricecake (AT) gehennom (DOT) net> wrote: Quote: True. After reading Jonathan's post, I will amend this to mean the standard C++ libraries, e.g., the STL. -- Marcus Kwok Back to top Heinz Ozwirk Guest Posted: Sat Oct 22, 2005 8:27 am    Post subject: Re: C program is standard C++ program? <strutsng (AT) gmail (DOT) com> schrieb im Newsbeitrag news:1129967908.534965.159700 (AT) g14g2000cwa (DOT) googlegroups.com... Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? No. Not every C program is also a valid C++ program. "new", "class" or "template" to name only a few, are valid identifiers in C, but they are reserved words in C++. So any C program using one of these identifiers is not a valid C++ program. Also void foo(); int main() { foo(1); } is legal in C, but not in C++ Quote: In a C++ program, we can use standard C libraries. However, we cannot use C++ libraries inside C program. Just that you can use C libraries in C++ does not imply that C is a subset of C++. You can also use Pascal or Fortran libraries in C++, but that is no reason to think that every Pascal or Fortran program is also a C++ program. Heinz Back to top Alex Vinokur Guest Posted: Sat Oct 22, 2005 8:37 am    Post subject: Re: C program is standard C++ program? [email]strutsng (AT) gmail (DOT) com[/email] wrote: Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? [snip] int main() { char a[3] = "foo"; return 0; } It is legal in C, but not in C++. Alex Vinokur email: alex DOT vinokur AT gmail DOT com http://mathforum.org/library/view/10978.html http://sourceforge.net/users/alexvn Back to top Emmanuel Delahaye Guest Posted: Sat Oct 22, 2005 9:26 am    Post subject: Re: C program is standard C++ program? [email]strutsng (AT) gmail (DOT) com[/email] a écrit : Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? No, it's not http://david.tribble.com/text/cdiffs.htm Unfortunately, this link seems to be down at the moment. Maybe, more information here : david at tribble dot com Quote: In a C++ program, we can use standard C libraries. However, we cannot use C++ libraries inside C program. Correct. -- C is a sharp tool Back to top Martin Ambuhl Guest Posted: Sat Oct 22, 2005 10:04 am    Post subject: Re: C program is standard C++ program? [email]strutsng (AT) gmail (DOT) com[/email] wrote: Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? It is a grossly erroneous statement. C and C++ are different languages. There are countless C programs that are not C++ programs. Back to top John Carson Guest Posted: Sat Oct 22, 2005 10:51 am    Post subject: Re: C program is standard C++ program? "Martin Ambuhl" <mambuhl (AT) earthlink (DOT) net> wrote Quote: strutsng (AT) gmail (DOT) com wrote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? It is a grossly erroneous statement. C and C++ are different languages. There are countless C programs that are not C++ programs. "C++ was developed from the C programming language and, with few exceptions, retains C as a subset." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., p. 8. -- John Carson Back to top Michael Mair Guest Posted: Sat Oct 22, 2005 11:23 am    Post subject: Re: C program is standard C++ program? John Carson wrote: Quote: "Martin Ambuhl" <mambuhl (AT) earthlink (DOT) net> wrote in message news:F8o6f.19590$q1.609 (AT) newsread3 (DOT) news.atl.earthlink.net [email]strutsng (AT) gmail (DOT) com[/email] wrote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? It is a grossly erroneous statement. C and C++ are different languages. There are countless C programs that are not C++ programs. "C++ was developed from the C programming language and, with few exceptions, retains C as a subset." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., p. 8. This may have been the intent; however, Martin's statement still is true as C++ semantics differ from C89 in many points. C99 introduced enough additional non-trivial differences which cannot be easily overcome. The C standard does not make any claim w.r.t. C++ compatibility, even though there may be a rationale saying exactly that. I do not own the C++ standard, so I cannot say anything from this point of view. Cheers Michael -- E-Mail: Mine is an /at/ gmx /dot/ de address. Back to top John Carson Guest Posted: Sat Oct 22, 2005 11:58 am    Post subject: Re: C program is standard C++ program? "Michael Mair" <Michael.Mair (AT) invalid (DOT) invalid> wrote Quote: John Carson wrote: "Martin Ambuhl" <mambuhl (AT) earthlink (DOT) net> wrote in message news:F8o6f.19590$q1.609 (AT) newsread3 (DOT) news.atl.earthlink.net [email]strutsng (AT) gmail (DOT) com[/email] wrote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? It is a grossly erroneous statement. C and C++ are different languages. There are countless C programs that are not C++ programs. "C++ was developed from the C programming language and, with few exceptions, retains C as a subset." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., p. 8. This may have been the intent; however, Martin's statement still is true as C++ semantics differ from C89 in many points. The statement that "C++ ... with few exceptions retains C as a subset" is not a statement of intent but a description of the relationship between the two languages, albeit one that seems to be directed at C89. I quote again: "With minor exceptions, C++ is a superset of C. Most differences stem from C++'s greater emphasis on type checking. Well-written C programs tend to be C++ programs as well." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., Appendix B, Compatibility, p. 816. Quote: C99 introduced enough additional non-trivial differences which cannot be easily overcome. That does indeed add to the incompatibility, though there are efforts underway to bring the two languages closer together, particularly by adding C99 stuff to C++. Quote: The C standard does not make any claim w.r.t. C++ compatibility, even though there may be a rationale saying exactly that. I do not own the C++ standard, so I cannot say anything from this point of view. Section 1.1/2 of the C++ standard: "C++ is a general purpose programming language based on the C programming language as described in ISO/IEC 9899:1990 Programming languages - C (1.2). In addition to the facilities provided by C, C ++ provides additional data types, classes, templates, exceptions, namespaces, inline functions, operator overloading, function name overloading, references, free store management operators, and additional library facilities." Annex C (appropriately enough) of the C++ standard deals with the relationship between C and C++, noting the areas of incompatibility. -- John Carson Back to top Rolf Magnus Guest Posted: Sat Oct 22, 2005 1:22 pm    Post subject: Re: C program is standard C++ program? John Carson wrote: Quote: "Well-written C programs tend to be C++ programs as well." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., Appendix B, Compatibility, p. 816. I tend to disagree. In C, dynamic memory is usually allocated with malloc or other functions that return a pointer to void. That pointer gets converted implicitly into the target type in C, and a cast should be avoided in a "well-written C program". However, in C++, it doesn't compile without a cast. Dynamic memory is something that is used quite often, so I'd say that most well-written C programs are not C++ programs and would need lots of changes (in all places where dynamic memory is allocated). Back to top John Carson Guest Posted: Sat Oct 22, 2005 1:59 pm    Post subject: Re: C program is standard C++ program? "Rolf Magnus" <ramagnus (AT) t-online (DOT) de> wrote Quote: John Carson wrote: "Well-written C programs tend to be C++ programs as well." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., Appendix B, Compatibility, p. 816. I tend to disagree. In C, dynamic memory is usually allocated with malloc or other functions that return a pointer to void. That pointer gets converted implicitly into the target type in C, and a cast should be avoided in a "well-written C program". However, in C++, it doesn't compile without a cast. Dynamic memory is something that is used quite often, so I'd say that most well-written C programs are not C++ programs and would need lots of changes (in all places where dynamic memory is allocated). Your point is covered in the preceding sentence: "Most differences stem from C++'s greater emphasis on type checking." But I guess that this preceding sentence somewhat gives the lie to the one that follows, so strictly speaking you are probably right that "most well-written C programs are not C++ programs". I am more sceptical about your claim that they would need "lots of changes". Well written C programs will hide most of the malloc calls inside initialization functions --- manual equivalents of constructors --- and the number of these shouldn't be very large. -- John Carson Back to top Michael Mair Guest Posted: Sat Oct 22, 2005 2:08 pm    Post subject: Re: C program is standard C++ program? John Carson wrote: Quote: "Michael Mair" <Michael.Mair (AT) invalid (DOT) invalid> wrote in message news:3rulqfFl484oU1 (AT) individual (DOT) net John Carson wrote: "Martin Ambuhl" <mambuhl (AT) earthlink (DOT) net> wrote in message news:F8o6f.19590$q1.609 (AT) newsread3 (DOT) news.atl.earthlink.net [email]strutsng (AT) gmail (DOT) com[/email] wrote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? It is a grossly erroneous statement. C and C++ are different languages. There are countless C programs that are not C++ programs. "C++ was developed from the C programming language and, with few exceptions, retains C as a subset." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., p. 8. This may have been the intent; however, Martin's statement still is true as C++ semantics differ from C89 in many points. The statement that "C++ ... with few exceptions retains C as a subset" is not a statement of intent but a description of the relationship between the two languages, albeit one that seems to be directed at C89. I quote again: "With minor exceptions, C++ is a superset of C. Most differences stem from C++'s greater emphasis on type checking. Well-written C programs tend to be C++ programs as well." Bjarne Stroustrup, The C++ Programming Language, 3rd ed., Appendix B, Compatibility, p. 816. Hmmm, my C code tends to look quite different from my C++ code. Things I find quite acceptable in C are not acceptable in C++ where better solutions to address certain problems exist. Apart from the different semantics of void* and ambiguities w.r.t. overloaded functions, there are better ways to perform explicit type conversions in C++ than the good old C-style cast. Quote: C99 introduced enough additional non-trivial differences which cannot be easily overcome. That does indeed add to the incompatibility, though there are efforts underway to bring the two languages closer together, particularly by adding C99 stuff to C++. Yes, AFAIR there were a couple of good articles by B.Stroustrup in CUJ about the areas where this is easily possible and where in his opinion, either C++ or C should change semantics. They may still be available online. Quote: The C standard does not make any claim w.r.t. C++ compatibility, even though there may be a rationale saying exactly that. I do not own the C++ standard, so I cannot say anything from this point of view. Section 1.1/2 of the C++ standard: "C++ is a general purpose programming language based on the C programming language as described in ISO/IEC 9899:1990 Programming languages - C (1.2). In addition to the facilities provided by C, C ++ provides additional data types, classes, templates, exceptions, namespaces, inline functions, operator overloading, function name overloading, references, free store management operators, and additional library facilities." Annex C (appropriately enough) of the C++ standard deals with the relationship between C and C++, noting the areas of incompatibility. Thank you for the information :-) Cheers Michael -- E-Mail: Mine is an /at/ gmx /dot/ de address. Back to top Branimir Maksimovic Guest Posted: Sat Oct 22, 2005 2:48 pm    Post subject: Re: C program is standard C++ program? <strutsng (AT) gmail (DOT) com> wrote Quote: I want if "a C program is a standard C++ program, but not vice versa" is a correct statement? In a C++ program, we can use standard C libraries. No we can't extern "C"{ void strcpy(char* restrict , const char* restrict); } Standard C++ compiler should spit error. Only non standard C++ compiler with appropriate extensions can use standard C libraries. However, we cannot Quote: use C++ libraries inside C program. Yes we can extern "C" void myfunc(int){ MyClass o; } // defines C function // that can be called from C Greetings, Bane. 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