Recent questions tagged C++

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c++ - What is Implicit constructors on Java

Is it mandatory to call base class constructor in Java? In C++ it was optional, so I am asking this. When ... & then it comes to derived right. 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++ - Can g++ fill uninitialized POD variables with known values?

I know that Visual Studio under debugging options will fill memory with a known value. Does g++ (any ... otherwise say should be uninitialized? 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++ - STL BigInt class implementation

Does STL have a BigInt class implementation? (numbers with many digits held into a container) 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 it undefined behavior to dereference a dangling pointer?

I can't find where in the standard that it says this program is undefined: #include <iostream> int main() ... lifetime seem to apply here. 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 Virtual Inheritance necessary for Exceptions?

I understand the need for virtual inheritance when using multiple inheritance -- it solves the Dreaded Diamond Problem. ... seem to find 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++ - Qt QNetworkReply is always empty

I want to see the results of a GET request. By my understanding, this code should do it. What am I doing wrong? ... fine. It just doesn't work. 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++ - Rule of Zero confusion?

So I have been reading about the Rule of Zero. Simplified version: I do not understand the purpose of this rule ... of confusion in one 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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c++ - Valgrind errors when linked with -static -- Why?

I have a test driver linked to a library I wrote. The library uses autotools so it produces both an archive (.a ... on 64-bit Redhat 5.5. 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++ - Release unmanaged memory from managed C# with pointer of it

The question in short words is : How to free memory returned from Native DLL as ItrPtr in managed code? ... am not native English speaker . 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++ - Ternary operator without the middle expression

I realized recently that you can use the ternary operator in GCC and clang without a middle (?: or ? : works) ... didn't see anything about 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++ - Multiple (diamond) inheritance compiles without "virtual", but doesn't with

Given the following code (without virtual inheritance) : class A { public: virtual void f() = 0; }; class ... it different in the second code ? 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++ - Always-in-front dialogs

Is there a way to create a modeless dialog box in C++ MFC which always stays on top of the other windows in the ... ; it's a dialog-based app) 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++ - Specifying font for many Text-elements in Qt QML

I have a widget specified through a QML file. This widget contains a top levelRectangle which contains two ... handwriting the QML files. 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++ - Affine Transform, Simple Rotation and Scaling or something else entirely?

The scenario goes like this: I have a picture of a paper that I would like to do some OCR. So take the ... it and get a more rectangular area. 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++ - What should happen to the negation of a size_t (i.e. `-sizeof(struct foo)`))?

I'm dealing with some code at work that includes an expression of the form -(sizeof(struct foo)) i.e. ... overflow' rules for unsigned values"? 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++ - Where can I get windows.h for Mac?

I'm trying to compile a program on MacOSX that I originally wrote on a Windows OS. The program is a large ... Mac or can something be salvaged? 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++ - boost::combine, range-based for and structured bindings

Is there a way to make boost::combine work with structured bindings and range-based for (so that identifiers in the ... << std::endl } } 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++ - Incorrect values when initializing a 2D array to 0 in gcc

#include <iostream> using namespace std; int main() { int rows = 10; int cols = 9; int opt[ ... incorrect (and potentially dangerous) behavior. 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++ - std::string and its automatic memory resizing

I'm pretty new to C++, but I know you can't just use memory willy nilly like the std::string ... handle growing and shrinking so transparently? 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++ - Unary plus (+) against literal string

Today I wrote an expression: "<" + message_id + "@" + + ">" ^ | \____ see that extra '+' here! ... operator is valid against a string literal!? 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 Run a cuda code using remote Desktop?

I am connecting to my desktop which has an Nvidia card (CUDA compatible) using remote desktop connection. I am ... I use other remote software? See Question&Answers more detail:os...

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

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262 views

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c++ - Signed right shift: which compiler use logical shift

I tested right shift with Visual Studio, Ubuntu's GCC, Intel compiler, MinGW. All shift in the sign bit. I guess ... in the sign bit? Thank you. 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 list files in a directory using the Windows API?

I have this code and it displays the folder with the directory itself and not its contents. I want to display ... hFind); } } Output: semester2 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++ - "printf" on strings prints gibberish

I'm trying to print a string the following way: int main(){ string s("bla"); printf("%s ", s); ... random gibberish. Can you please explain why? 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++ - Non-trivial destructor make class non-trivially-constructible

Consider following code: #include <type_traits> struct T {}; static_assert(std::is_trivially_destructible< T >{}); ... there is workaround too. 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++ - Bit-fields "In-class initialization" results in "error: lvalue required as left operand of assignment"

struct bitfield { int i = 0; // ok int j : 8 = 0; // error: lvalue required as left operand of ... C++11 "in-class initialization" feature? See Question&Answers more detail:os...

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

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284 views

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c++ - Are system() calls evil?

I am designing an C++ app that, among other things, executes a few scripts every now and then. The app should ... system()? ) Any other issues? 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++ - Detecting reason for failure to open an ofstream when fail() is true

Seems like this should be simple, but I don't find it in a net search. I have an ofstream which is open ... errno I would do sys_errlist[errno]. See Question&Answers more detail:os...

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

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