Re:The Ten Commandments for C Programmers (1987)
by burfog on Sunday May 24, 2020 @12:32AM
(#23289097)
Some of that capability is there only to overcome optimization problems that were created by C++ features. You don't need to make the compiler aware that some values are "going away" soon if that is clearly obvious. Without layer upon layer of object obfuscation, optimization is a much easier problem.
In C too, functions are removed entirely in favor of the results. This is a quality-of-implementation issue. There are good and bad compilers for most languages. C is less dependent on compiler quality however, with relatively simple compilers being able to produce good output for stylistically typical code.
Yes, in several ways, including:
* Move semantics - you can make the compiler aware that some values are "going away" soon and can be cannibalized rather than conserved. * Compile-time execution - a significant (and growing) subset of the language can simply be computed at compile-time rather than run-time. So if you have a certain function which computes something - anything that doesn't involve I/O (and until C++20 - uses a fixed amount of memory), and your inputs are known in advance, the function won't have to run whenever you run the program, but would be removed entirely in favor of the result.
To see how these and other language features combine to allow for highly-efficient code, check out this video:
CppCon 2016: Jason Turner “Rich Code for Tiny Computers: A Simple Commodore 64 Game in C++17” https://www.youtube.com/watch?v=zBkNBP00wJE
Where you write an implementation of the Pong game - with high-level, straightforward code, and no "dirty tricks" - whose compilation result requires exactly 0 stack and 0 heap space.