C++ vs. C

From Pin Eight
Revision as of 16:24, 5 July 2010 by Tepples (talk | contribs) (This would probably get a C-)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

C++ vs. C


Compared to C, C++ has a bunch of new language features with little or no runtime overhead because they are translated to code equally as efficient as the equivalent C code:

  • namespace
  • references
  • function overloading
  • type-safe new(std::nothrow)
  • STL, the part of the C++ standard library with containers and algorithms
  • non-virtual methods

A few features are as efficient as C yet still rawther deceptive and easy to misuse because the "simple" syntax hides how much code is actually being generated:

  • operator overloading, when compared to separate functions
  • virtual methods, when compared to C function pointer tables
  • templates, when compared to using the preprocessor to instantiate multiple copies


C++ also has some features requiring possibly expensive runtime library support:

  • throw
  • the default version of new without std::nothrow, which throws exceptions and is used internally by the standard library
  • <iostream>

Templates have a couple drawbacks:

  • more complicated error messages
  • programmers who lose track of for how many different type combinations they have instantiated a template, causing code size to balloon

Exceptions (throw) also have a couple drawbacks:

  • The size of the required library support might cause a problem on embedded or handheld devices with little RAM.
  • C++ has no counterpart to the finally keyword of Java and Python. True, there isn't as much need for finally in C++ as in languages that rely on a garbage collector, given the idiom of allocating resources in constructors that C++'s deterministic destruction allows. But a method often still needs to restore the object's fields to a consistent state before eating or rethrowing the exception.

Apparently one STL implementation can be built without the use of exceptions: STLPort.[1] I'd be interested to hear about whether it has worked for you.

The <iostream> library is another divisive issue. It was envisioned as a type-safe alternative to <cstdio>, but implementations are hairy, bloated, inefficient. Yet some C++ fanboys claim that anything using good old <cstring> and <cstdio> instead of new-fangled <string> and <iostream> isn't in the spirit of C++, whatever that means. They cling to item 2 in the second edition of Scott Meyers Effective C++ and ignore item 23 of his sequel ("consider alternative libraries"). It appears that Meyers eventually recognized that <iostream> is imperfect and removed item 2 from the third edition.

External links

  • C++ FQA Lite, offering a rebuttal to the fandom's C++ FAQ Lite