Stack Overflow Weekly Newsletter
Stack Overflow Weekly Newsletter

Top new questions this week:

What is the >>>= operator in C?

Given by a colleague as a puzzle, I cannot figure out how this C program actually compiles and runs. What is this >>>= operator and the strange 1P1 literal? I have tested in clang and GCC. There are …

c obfuscation literals bit-shift-operators digraphs  
asked by CustomCalc 191 votes
answered by Ilmari Karonen 334 votes

Go isn't linking my assembly: undefined external function

I'm trying to write some SIMD mostly for learning purposes. I know Go can link assembly, but I can't get it to work correctly. Here's the most minimal example I can make (element-wise vector …

assembly go  
asked by Jsor 62 votes
answered by FUZxxl 77 votes

C++ :: why is there injected class name?

Recently, I saw the strange C++ feature, injected class name. class X { }; X x1; class X::X x2; // class X::X is equal to X class X::X::X x3; // .. and so on.. But I cannot figure out why this …

asked by ikh 43 votes
answered by Jonathan Wakely 51 votes

Is it a premature optimization to use std::move()?

Suppose I have the following code: int main() { std::vector<std::string> strs; std::string var("Hello World"); // Make some modifications to 'var' …

c++ c++11  
asked by Robert Dailey 43 votes
answered by Jonathan Wakely 19 votes

Why is "" == [null] true in JavaScript?

I know JavaScript has lots of insane results with comparisons between types, though I don't fully understand why. Came across this one today. Why does "" == [null] evaluate to true in …

asked by Scott Stafford 30 votes
answered by Pointy 50 votes

Zipper Comonads, Generically

Given any container type we can form the (element-focused) Zipper and know that this structure is a Comonad. This was recently explored in wonderful detail in another Stack Overflow question for the …

haskell zipper deriving comonad  
asked by J. Abrahamson 28 votes
answered by pigworker 30 votes

Program with loop will not terminate with CTRL + C

I have a program that I want to run until interrupted by user pressing CTRL + C. When I press it nothing happens and I can only terminate the program by suspending it and manually killing it after …

c infinite  
asked by humra 28 votes
answered by Paul R 56 votes

Greatest hits from previous weeks:

Why is the Android emulator so slow?

I have a 2.67 GHz Celeron processor, 1.21 GB of RAM on a x86 Windows XP Professional machine. My understanding is that the Android emulator should start fairly quickly on such a machine, but …

android performance android-emulator qemu  
asked by Andrie 1443 votes
answered by Vikas Patidar 693 votes

no exports were found that match the constraint contract name

This morning I faced a problem while opening my Visual Studio solution and when I tried to run it. It said "no exports were found that match the constraint contract name" Then I made some research …

asked by Simon B.Robert 361 votes
answered by Simon B.Robert 701 votes

Can you answer these?

How can I make Code Contracts ignore a specific assembly reference?

I'm making an extension to Visual Studio. Within the code I'm using Code Contracts to make assertions and checks. I set the warning option level to high. What I would like to do is maintain that …

c# .net visual-studio code-contracts  
asked by Crono 4 votes

How are dynamic priorities of threads computed in Linux 2.6.x?

A thread (or task) will loss dynamic priority by using a lot of cpu and gain priority by using less of CPU. How exactly are these priorities computed for n threads (using normal scheduling policy …

c linux operating-system pthreads scheduled-tasks  
asked by Shan 4 votes

What is the fastest way to extract given rows and columns from a Numpy ndarray?

I have a large (approx. 14,000 x 14,000) square matrix represented as a Numpy ndarray. I wish to extract a large number of rows and columns--the indices of which I know in advance, though it will in …

python optimization numpy scipy linear  
asked by jveldridge 4 votes
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