standards

问题 This question already has answers here : What's the difference between Array(1) and new Array(1) in JavaScript? (3 answers) What is the 'new' keyword in JavaScript? (14 answers) Closed 5 years ago . Playing with built-in JavaScript objects and constructors, I noticed something a little odd. Sometimes, it's possible to get new objects by calling a constructor without new . For example: > new Array(1,2,3,4) [1, 2, 3, 4] > Array(1,2,3,4) [1, 2, 3, 4] But sometimes this doesn't work: > Date()

问题 This question already has answers here : What's the difference between Array(1) and new Array(1) in JavaScript? (3 answers) What is the 'new' keyword in JavaScript? (14 answers) Closed 5 years ago . Playing with built-in JavaScript objects and constructors, I noticed something a little odd. Sometimes, it's possible to get new objects by calling a constructor without new . For example: > new Array(1,2,3,4) [1, 2, 3, 4] > Array(1,2,3,4) [1, 2, 3, 4] But sometimes this doesn't work: > Date()

问题 This question already has answers here : Is main() overloaded in C++? (6 answers) Closed 2 years ago . Since C+++ allows function overloading, can we overload main() ? For example, int main(const std::string &) { return 0; } int main(int argc, char *argv[]) { return main("calling overloaded main"); } gcc-4.3.4 doesn't compile this, and gives these errors: (see at ideone) prog.cpp:4: error: first argument of ‘int main(const std::string&)’ should be ‘int’ prog.cpp:4: error: ‘int main(const std:

问题 This question already has answers here : Is main() overloaded in C++? (6 answers) Closed 2 years ago . Since C+++ allows function overloading, can we overload main() ? For example, int main(const std::string &) { return 0; } int main(int argc, char *argv[]) { return main("calling overloaded main"); } gcc-4.3.4 doesn't compile this, and gives these errors: (see at ideone) prog.cpp:4: error: first argument of ‘int main(const std::string&)’ should be ‘int’ prog.cpp:4: error: ‘int main(const std:

问题 Following the guidelines proposed in this post, I am changing all the from module import function function(agt) by: import module as mdl mdl.function(agt) in my codes. I am trying to use commonly used aliases rather than personal ones. Is there a list of some kind on the internet summing-up all well-used aliases ? For instance, these appear to be pretty common: import numpy as np import math as m import matplotlib.pyplot as plt What about aliases for scipy.linalg , time , scipy.io , cmath and

问题 If we look at the Java standard §14.7, we see that statements may have label prefixes, e.g.: LabeledStatement:       Identifier : Statement In theory, a label should be able to label any succeeding statement. So, for example, the following compiles accordingly: public class Test { public static void main(String[] args) { hello: return; } } Intuitively, this also compiles: public class Test { int i; public static void main(String[] args) { Test t = new Test(); label: t.i = 2; } } But the

问题 The C++ standard provides the std::set_terminate function which lets you specify what function std::terminate should actually call. std::terminate should only get called in dire circumstances, and sure enough the situations the standard describes for when it's called are dire (e.g. an uncaught exception). When std::terminate does get called the situation seems analagous to being out of memory -- there's not really much you can sensibly do. I've read that it can be used to make sure resources

问题 This is a nitpicky-details question with three parts. The context is that I wish to persuade some folks that it is safe to use <stddef.h> 's definition of offsetof unconditionally rather than (under some circumstances) rolling their own. The program in question is written entirely in plain old C, so please ignore C++ entirely when answering. Part 1: When used in the same manner as the standard offsetof , does the expansion of this macro provoke undefined behavior per C89, why or why not, and

问题 I've (finally) been reading up on PEAR (php) coding standards. What is the purpose of commenting like this: /** * Here is my comment * I Wrote this in a haiku * But why put the stars? */ As opposed to this: /* Here is a comment No haiku or anything special, but it still works! */ 回答1: The /** stuff */ document is also referred to as DocBlock notation. It's used to document PHP functions, classes, etc. /** * A test function * * @param foo $bar * @return baz */ function test(foo $bar) { return

问题 Strict aliasing prevents us from accessing the same memory location using an incompatible type. int* i = malloc( sizeof( int ) ) ; //assuming sizeof( int ) >= sizeof( float ) *i = 123 ; float* f = ( float* )i ; *f = 3.14f ; this would be illegal according to C standard, because the compiler "knows" that int cannot accessed by a float lvalue. What if I use that pointer to point to correct memory, like this: int* i = malloc( sizeof( int ) + sizeof( float ) + MAX_PAD ) ; *i = 456 ; First I