I had no idea, so I googled to find something about this. This is what I found. First, it was included as a reserved keyword. Q: What was the entry keyword mentioned in K&R1? A: It was reserved to allow functions with multiple, differently-named entry points, but it has been withdrawn. (From http://archives.devshed.com/forums/c-c-134/c-programming-faqs-371017.html.) It was … Read more
Pretty simple: Implicit widening conversions on unsigned types do not change the result. Implicit widening conversions on signed types (including promotions) perform sign-extension, which does change the result if the input was negative. Having an operation whose result becomes incorrect due to integer promotion definitely falls into the “foot cannon” category. You can still feed … Read more
You can’t properly implement many of the std::complex operations on integers. E.g., template <class T> T abs(const complex<T> &z); for a complex<long> cannot have T = long return value when complex numbers are represented as (real,imag) pairs, since it returns the value of sqrt(pow(z.real(), 2) + pow(z.imag(), 2)). Only a few of the operations would … Read more
Because someone in the C++ standards committee thought that it was a good idea to allow this code to work: struct foo { int blah; }; struct thingy { int data; }; struct bar : public foo { thingy foo; }; int main() { bar test; test.foo.data = 5; test.foo::blah = 10; return 0; } … Read more
Erlang was designed for use in Telecommunication systems, where high-rel is fundamental. I think they have standard methodology for building sets of communicating processes in which failures can be gracefully handled. ERLANG is a concurrent functional language, well suited for distributed, highly concurrent and fault-tolerant software. An important part of Erlang is its support for … Read more
Note that the regex need not be recompiled each time. From the Javadoc: An invocation of this method of the form str.split(regex, n) yields the same result as the expression Pattern.compile(regex).split(str, n) That is, if you are worried about performance, you may precompile the pattern and then reuse it: Pattern p = Pattern.compile(regex); … String[] … Read more
I believe that their main reason was portability of programs targeting CLR. If they were to allow a type as basic as int to be platform-dependent, making portable programs for CLR would become a lot more difficult. Proliferation of typedef-ed integral types in platform-neutral C/C++ code to cover the use of built-in int is an … Read more
Lets start out with a silly but illustrative example: Object o = 15; o = “apples”; At no point do we get the impression that we just turned the number 15 into a string of apples. We know that o is simply a pointer. Now lets do this in iterator form. int[] nums = { … Read more
Null: The Billion Dollar Mistake. Tony Hoare: I call it my billion-dollar mistake. It was the invention of the null reference in 1965. At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W). My goal was to ensure that all use of references should be … Read more