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Question: >>> timeit.timeit("'x' in ('x',)") 0.04869917374131205 >>> timeit.timeit("'x' == 'x'") 0.06144205736110564 Also works for multiple options, both seem to grow linearly: >>> timeit.ti

Question： When returning a local object by value, C++ compilers may optimize out unnecessary copies (copy elision) by taking advantage of the move semantics. "may optimize" implies that if proper

#include int f(int x) { return x?:1; } int main() { printf("f %d\n", f(0)); printf("f %d\n", f(1)); return 0; } And got the following output f 1 f 1 And when I

Question: So lets say I have a struct like this: struct example_structure { int thing_one; int thing_two; }; I also have an empty array which I am trying to fill with these structs. I am tryin

Question: Editor's clarification: When this was originally posted, there were two issues: Test performance drops by a factor of three if seemingly inconsequential statement addedTime taken to

Question: I was testing some code on Coliru, and I got a strange output. I went down the code and could reproduce it with this simple piece of code: int main() { π } The output on g++

Question: I have a matrix, for example A = [ 1 2 3; 4 5 6; 7 8 9] ; and a vector of size 1x3 which specifies which element in each row is the one I'm looking for - i.e. If vector = [ 1 2 1 ]

Question: So we are used to say to every R new user that "apply isn't vectorized, check out the Patrick Burns R Inferno Circle 4" which says (I quote): A common reflex is to use a function in t

Question: I have a use case where I can get pointers of strings allocated either in memory or literals. Now the latter can't be freed so that's a problem if I pass the wrong one. Is there a way to kn

Question: In the various cases that a buffer is provided to the standard library's many string functions, is it guaranteed that the buffer will not be modified beyond the null terminator? For examp

Question: I can't believe I am typing a question for a simple thing like this but here we are. I can't for the life of me figure out what the exact name for the settings file is for vim on Wi

Question: I have by pure chance discovered that the C# compiler turns this method: static bool IsNotNull(object obj) { return obj != null; } …into this IL: .method private hidebysig static

Question: I was testing some code on Coliru, and I got a strange output. I went down the code and could reproduce it with this simple piece of code: int main() { π } The output on g+

Question: What is the difference from NULL and "0"? Example: return NULL; return 0; Answer: Conceptually, zero (0) is a number, and NULL is a value that represents "no value". As such, 0 ca

Question: I'm having trouble understanding this line: rear->next = temp; in this queue function: void Queue::enqueue(int data) { Node *temp = new Node(); // make a temporary node te

我们很多朋友都给我留言说，希望我翻译一下stackoverflow的问题以及答案，首先我也非常愿意为大家翻译，在可以帮助大家的同时，对我本人的技能的提升有好处；但是工作量实在太大，所以我不可能翻译所有的文章，尽力吧

Question： Could you please explain, why does Console.WriteLine write empty line (Console.WriteLine(null)give me compilation error) and why there isn't NullReferenceException (even a+=1 shouldn't

Question: I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug. Is == b

Question: I have this if statement: if (input == 'day') Console.Write({0}, dayData); When the user types 'day' it should be so that the console writes the data in that array. It works fine

Quesion: My question arises from one of my c++ exercises (from Programming Abstraction in C++, 2012 version, Exercise 12.2). Here it is: void strcpy(char *dst, char *src) { while (*dst++ = *sr

Question: I have been getting my feet wet with android sdk, eclipse, and other various beginner steps to making applications; now I want more. I have ordered some books from my local library which i

Question: But I completely have no idea what I wanted to make. I just would like to study android.Would someone recommend me a simple project which takes one or two months to build?Either it is r

Question: #include int main() { std::cout "25"+1; return 0; } I am getting "5" as output.when I use "5"+1,output is blank;"456"+1 output is "56".confused what is going behind the scenes.

Question: Suppose a1, b1, c1, and d1 point to heap memory and my numerical code has the following core loop. const int n=100000 for(int j=0;jn;j++){ a1[j] += b1[j]; c1[j] += d1[j]; } T

Question： In what scenarios is it better to use a struct vs a class in C++? Answer： The only difference between a class and a struct in C++ is that structs have default public members and b

Question： This question was already asked in the context of C#/.Net. Now I'd like to learn the differences between a struct and a class in C++. Please discuss the technical differences as well

Question： What does copying an object mean? What are the copy constructor and the copy assignment operator? When do I need to declare them myself? How can I prevent my objects from being copied

Question： I know references are syntactic sugar, so code is easier to read and write. But what are the differences? Summary from answers and links below: A pointer can be re-assigned

I open several files in Vim by, for example, running vim a/*.php which opens 23 files. I then make my edit and run the following twice :q which closes all my buffers. How can you close

When I create a function, I can put the code for it after main if I put the prototype above main. For example, int myFunction(int a) { return(a); } would have the prototype.. int myFunction(int a)

Question: I'm less than a year into C++ development (focused on other languages prior to this) and I'm looking at a guy's code who's been doing this for two decades. I've never seen this syntax b

都是程序员，想必都对stackoverflow有一定的了解，这个网站是世界上最为活跃的编程知识的论坛网站，上面活跃着数以万计的大神、提问各种有意义有价值的问题，还有这些问题的详细的回答。 但是毕竟是国外的网站，需要一定得语言的基础，所以对于中国人来说，这是一种劣势，所以我想利用我在加拿大学习工作所积累的词汇量，帮助大家尽量的筛选出对有价值的问题和回答。 我会每天在我的博客里，转

What is Branch Prediction? Consider a railroad junction: Image by Mecanismo, via Wikimedia Commons. Used under the CC-By-SA 3.0 license. Now for the sake of argument, suppose this is back in th

Question： I'm working on a data structures course and I'm not sure how to proceed w/ this Big O analysis: sum = 0; for(i = 1; i < n; i++) for(j = 1; j < i*i; j++) if(j % i == 0)

Question: I accidentally found: cout cout; The output is some address. What does this address mean, and why is it shown? I am looking this question. Answer: Because ostream overload o