Recent questions tagged C++

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c++ - can't use structure in global scope

I defined struct in the global scope, but when I try to use it, I get error: co' does not name a type ... just cannot be used in global scope? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Arc in QGraphicsScene

I want to implement arc in QGraphicsScene. I want that on clicking of three points my arc should be drawn such ... me out to solve the error. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Using an union (encapsulated in a struct) to bypass conversions for neon data types

I made my first approach with vectorization intrinsics with SSE, where there is basically only one data type ... aligned attribute necessary?) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Generate all sequences of bits within Hamming distance t

Given a vector of bits v, compute the collection of bits that have Hamming distance 1 with v, then with distance 2, up to ... 1 1 0 0 1 0 1 0 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why does rand() return the same value using srand(time(null)) in this for loop?

I have the following code #include<iostream> #include "time.h" using namespace std; void printRandomNumber() { srand( ... out a mix of numbers. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Combining two lists by key using Thrust

Given two key-value lists, I am trying to combine the two sides by matching the keys and applying a ... are thrust::device_vector<int>. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - how to swap array-elements to transfer the array from a column-like into a row-like representation

For example: the array a1, a2, a3, b1, b2, b3, c1, c2, c3, d1, d2, d3 represents following table ... do the job with element-swap operations. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to store a reference of a singleton class?

I am working on a project relating to a dealer dealing cards to players. I have the singleton class Dealer ... to the singleton Dealer instance? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Referencing memory operands in .intel_syntax GNU C inline assembly

I'm catching a link error when compiling and linking a source file with inline assembly. Here are the test files: via: ... and how do I fix it? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why can't I assign an array variable directly to another array variable with the '=' operator?

Why does the following assignment not work? I would like a low-level explanation if possible. Also, here's the compiler ... ); //works } }; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to solve -------undefined reference to `__chkstk_ms'-------on mingw

I have just install gcc and g++ on mingw. I wrote a very simple "hello world" program to test if the ... collect2: ld returned 1 exit status See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - error LNK2019 unresolved external symbol

I am quite new to C++ so I downloaded a sample C++ program. The sample program seems to hit the ... would very much be appreciated. Thanks See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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349 views

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c++ - Copy constructor elision?

Don't quite understand why this copy constructor is not invoked when I build with debug mode using VC2010. ... it omit the copy constructor. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - int var = 1; void main() { int i = i; }

This is an interview question that I had: int var = 1; void main() { int i = i; } What is the value of ... to give me 0 all the time. Thanks See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Explicitly initialize DWORD to 1, but debugger shows wildly out of range value

I'm a bit flabberghasted with this issue - in debug mode this issue doesn't come up at all, but in release ... Debug mode this code runs fine. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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131 views

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c++ - how does url within function body get compiled

I just pasted a url to my code, and forgot to comment it, but I was surprised to see MSVC++ compiled it ... come this gets compiled by MSVC++? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to require an exact function signature in the detection idiom?

Let's suppose I have a type T and I want to detect whether it has a subscript operator which I can call with ... int to size_t to take place? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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119 views

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c++ - Do you know tool building tree of include files in projectfile?

Say, I'd like to have a tool (or script?) taking project (or .h file) and building searchable tree of "includes" ... has an idea how to get it]? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Macros in the middle of a class or function declaration

I've read related questions like this and this, and other pages, but they don't really answer my question. ... that would be much appreciated. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Size of the classes in case of virtual inheritance

Can someone please explain about the size of the classes in the case of virtual inheritance involving virtual functions. ... 4.6.1-9ubuntu3) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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243 views

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c++ - Reading and writing a std::vector into a file correctly with iterators

I'm trying to understand the answer provided here, but I can't seem to make it work. Here is what ... be updated to populate newVector? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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174 views

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c++ - What is the purpose of forward declaration?

what is the description or meaning of this: for example: class test; class test { ..... }; See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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283 views

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c++ - how to set pointer to a memory to NULL using memset?

I have a structure typedef struct my_s { int x; ... } my_T; my_t * p_my_t; I want to set the ... careful thinking about what is going on. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is uninitialized data behavior well specified?

Note: I am using the g++ compiler (which is I hear is pretty good and supposed to be pretty ... completely understanding the inheritance stuff.. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Other's library #define naming conflict

Hard to come up with a proper title for this problem. Anyway... I'm currently working on a GUI for my ... to avoid them all together. Cheers! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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372 views

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c++ - Windows Media Foundation recording audio

I'm using the windows media foundation api to enumerate both my microphones and available cameras, which both work. ... into my video encoding. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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224 views

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c++ - How does calling srand more than once affect the quality of randomness?

This comment, which states: srand(time(0)); I would put this line as the first line in main() instead if ... Can somebody clear this up for me? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - clang vs gcc - optimization including operator new

I have this simple example I was testing against and I noticed that gcc optimizations (-O3) seems not be as ... something which is not allowed? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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