compilation

问题 I am a little bit confused about the following piece of code: public class Test{ int x = giveH(); int h = 29; public int giveH(){ return h; } public static void main(String args[]) { Test t = new Test(); System.out.print(t.x + " "); System.out.print(t.h); } } The output here is 0 29 , but I thought that this has to be a compiler error, because the variable h should have not been initialized when it comes to the method giveH() . So, does the compilation go through the lines from top to bottom?

问题 What's the best value of -j switch? I usually set this up to the number of CPU/Cores available. Thanks. 回答1: I've always seen the number of cores available plus 1 as the recommended value 回答2: Just measure. Start with the number of cores. And then add one until you feel that you get diminishing returns. 来源： https://stackoverflow.com/questions/3025587/whats-best-value-for-make-j

问题 From this question: Why do you have to link the math library in C? I know that C math library (libm) is separated from C standard library (libc), and is not linked in by default. But when I compiled the code below using gcc filename.c without -lm on mac osx 10.11.1 : #include <math.h> #include <stdio.h> int main (void) { double x = sqrt (2.0); printf ("The square root of 2.0 is %f\n", x); return 0; } There's no link error and the output executable file works correctly. Then I tried otool -L

问题 I have following installed on my system - Java version "1.7.0_09" JavaFX 2.0 SDK NetBeans 7.2.1 When I am trying to compile the code using ANT it showing me error message - Could not load definitions from resource com/sun/javafx/tools/ant/antlib.xml. It could not be found. Build.XML contains <project name="XYZ" default="XYZ" basedir="XYZ" xmlns:fx="javafx:com.sun.javafx.tools.ant"> <description> simple example build file </description> <!-- set global properties for this build --> <property

问题 Usually in C++ when I need interdependencies between classes, I use forward declarations in the header files and then include both header files in each cpp file. However this approach breaks when working with templates. Because templates have to be entirely in the header files (not counting the case when I put the code into cpp and enumerate template class A<T>; for each supported T - this is not always feasible, e.g. when T is a lambda). So is there a way to declare/define interdependent

问题 http://www.vex.net/~trebla/haskell/so.xhtml describes how to compile shared library. About compiling command: ghc -O2 -dynamic -shared -fPIC -o libEval.so Eval.hs hsbracket.c -lHSrts-ghc7.6.3 it says: (Could you omit -dynamic to request static libraries of other packages? Not really, they were not generated with -fPIC. In particular it is illegal on x86_64.) Why is it so? What should one do to compile shared library without libHS* dependencies? 回答1: Since Kaiko contacted me privately for an

问题 I would like to cythonize faster. Code for one .pyx is from distutils.core import setup from Cython.Build import cythonize setup( ext_modules = cythonize("MyFile.pyx") ) What if i want to cythonize several files with ext .pyx, that i will call by their name all .pyx files in a folder What would be python code for the setup.py in both cases ? 回答1: From: https://github.com/cython/cython/wiki/enhancements-distutils_preprocessing # several files with ext .pyx, that i will call by their name from

问题 I started to fiddle with PyQt, and made a "beautiful" script from the pyqt whitepaper example app (pastebin) It works perfectly in Windows and Linux (with qt environment already installed on both). Now my question is: Since I am trying to use Qt because it is compiled (at least pure old C++ based Qt), how can I compile some .exe file to run it on Windows, or a standalone executable for Linux. The point is that I want the program to be compiled, because of speed and portability, instead of

问题 I started to fiddle with PyQt, and made a "beautiful" script from the pyqt whitepaper example app (pastebin) It works perfectly in Windows and Linux (with qt environment already installed on both). Now my question is: Since I am trying to use Qt because it is compiled (at least pure old C++ based Qt), how can I compile some .exe file to run it on Windows, or a standalone executable for Linux. The point is that I want the program to be compiled, because of speed and portability, instead of

问题 You can compile Python in various ways. I'd like to find out with which options my Python was compiled. Concrete use-case: was my Python compiled with readline? I know I can see this by doing "import readline", but I'd like to see a list of compilation setting for my Python binary. Edit: I mean the Python executable and not source code written by myself. 回答1: There is a module to see the system config import sysconfig print(sysconfig.get_config_vars()) It offers an interface to get individual