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What features were added to C that were originally in C++?
When where they added and for what reason(what where the pro/con arguments)?
How do they differ in C as compared to C++?

Did the features originate in C++ or in another language?

Examples (feel free to expand on): const, Function prototypes, implicit exit(0);

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4 Answers

up vote 11 down vote accepted

A few that I can think of that were added for C99. bool is not quite the same as C++ since you need to include a header to use it, the others are implemented the same as C++.

  • bool / true / false
  • // comments
  • inline functions
  • variables don't need to be declared at start of block
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The bool type in C99 is _Bool. bool is just a macro in stdbool.h expanding to _Bool. Similarly true and false are macros for 1 and 0. I'm pretty sure they implemented it in this way give the programmer the option to be compatible with C++. –  user29079 Aug 12 '11 at 13:55
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Same answer than in SO: the best and most pertinent source is Bjarne's paper. You could probably grab one piece of information or another in sources like The Design and Evolution of C++ or the papers on the history of C and C++ in the proceedings of HOPL, but I don't remember anything specific there, especially in the direction C++ to C.

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The only technical differences I'm aware of migrating in that direction are the C99 enhancements like not having to declare variables at the start of functions. A number of style items migrated due to the fact that C programs are occasionally compiled with C++ compilers to be included as part of a C++ program. This includes avoiding the use of C++ reserved words like "class" and gratuitous typecasts (like on the result of malloc) that are required in C++ but are implicit in C.

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Didn't "line" style comments (//such as this example) also go from C++ to C? –  FrustratedWithFormsDesigner Aug 10 '11 at 13:36
@FrustratedWithFormsDesigner Actually they went from B to C++ to C. –  h0b0 Aug 10 '11 at 14:08
Line-style comments were one of the C99 enhancements, @Frustrated. However, I do remember those being one of the more popular unofficial compiler-specific extensions long before they were formalized as a standard. –  Karl Bielefeldt Aug 10 '11 at 15:20
I suspect that typecasting the result of functions returning void, such as malloc, is most commonly caused by confused C programmers trying to compile their code on a C++ compiler, and less commonly an intention to be C++ compatible. It should also be mentioned that typecasting the result of void* functions in C is considered bad practice, as it effectively disables a number of static type checks that the compiler and/or external tools could otherwise have done to find bugs. –  user29079 Aug 12 '11 at 14:07
The malloc cast topic is discussed in detail in countless SO threads such as this one. –  user29079 Aug 12 '11 at 14:07
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basically C++ comes from C, the common part between both languages is called C- . The C++ is "bigger/better" than C, but the main thing is that it's a fully object oriented programming language and C isn't.

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Well current C and C++ share a common ancestor (say K&R C), but there are strong cross-influence (positive or negative, one sometimes get the impression that some want to increase the incompatibility between the two). –  AProgrammer Aug 10 '11 at 11:42
C++ is a superset of C, but it's not strict. So you wind up with code that is valid C such as void *ptr; int *ptr2 = ptr; which is not valid in C++. This is in contrast to something like Objective C, which is a strict superset of C. Because of this, "all" valid C code is also valid Objective C code. –  Barry Aug 10 '11 at 15:45
I've never heard of C- before, though I have heard of C--. Do you have any reliable source for this C- thing? –  user29079 Aug 12 '11 at 14:10
I read it long ago on a C++ book. I would have to consult that book to assure such a thing. –  Feida Kila Aug 30 '11 at 13:38
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