Recent questions tagged C++

0 votes

445 views

1 answer

c++ - Is self-initialization 'A a = a;' allowed?

This code fails at runtime in the copy constructor. But the compiler (MSVS2008) issues no warnings. Could you explain ( ... { A a = a; } See Question&Answers more detail:os...

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

0 votes

628 views

1 answer

c++ - Passing pointer argument by reference under C?

#include <stdio.h> #include <stdlib.h> void getstr(char *&retstr) { char *tmp = (char *)malloc(25); strcpy( ... reference? If not, why? Thanks. See Question&Answers more detail:os...

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

0 votes

864 views

1 answer

c++ - How do I pass a std::function object to a function taking a function pointer?

I am trying to interface with a library written in c, that uses this familiar pattern: void some_c_handler(void( ... handler. Is this possible? See Question&Answers more detail:os...

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

0 votes

511 views

1 answer

c++ - Returning 'c_str' from a function

This is from a small library that I found online: const char* GetHandStateBrief(const PostFlopState* state) { ... the string be accessed? See Question&Answers more detail:os...

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

0 votes

651 views

1 answer

c++ - Compile-time error: Multiple definition of 'main'

I am getting the following error: Multiple definition of `main' I have created a new project, there are two c++ ... How do I run these files? See Question&Answers more detail:os...

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

0 votes

757 views

1 answer

c++ - Covariant return type and type conversion

s->duplicate() returns an object of type Box*, but I'm getting an error initializing it with Box*. It looks like ... ~~~~~~~ 1 error generated. See Question&Answers more detail:os...

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

0 votes

724 views

1 answer

c++ - Allocating struct with variable length array member

I know I can do new char[n] to create an array of n chars. This works even when n is not a ... presumably what std::string already does)? See Question&Answers more detail:os...

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

0 votes

494 views

1 answer

c++ - Is it UB to access a member by casting an object pointer to `char *`, then doing `*(member_type*)(pointer + offset)`?

Here's an example: #include <cstddef> #include <iostream> struct A { char padding[7]; int x; }; constexpr ... . No definitive answer was given. See Question&Answers more detail:os...

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

0 votes

655 views

1 answer

c++ - How to send keystrokes to a window?

im using keybd_event(); and i want use SendMessage(); to send keystroke to notepad, can this be done? See Question&Answers more detail:os...

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

0 votes

744 views

1 answer

c++ - Parse int or double using boost spirit (longest_d)

I'm looking for a way to parse a string as an int or a double, the parser should try both alternatives ... , does anyone have a suggestion? See Question&Answers more detail:os...

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

0 votes

1.2k views

1 answer

c++ - How can I save HICON to an .ico file?

I am extracting an icon from .exe/.dll and want to save it in an .ico file. What is the best way to do ... .icl files/etc. Please, help. Thanks. See Question&Answers more detail:os...

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

0 votes

527 views

1 answer

c++ - Very simple application fails with "multiple target patterns" from Eclipse

Since I'm more comfortable using Eclipse, I thought I'd try converting my project from Visual Studio. Yesterday I ... m willing to try anything! See Question&Answers more detail:os...

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

0 votes

598 views

1 answer

c++ - Get sum of values stored in __m256d with SSE/AVX

Is there a way to get sum of values stored in __m256d variable? I have this code. acc = _mm256_add_pd(acc ... it with SSE/AVX instruction. See Question&Answers more detail:os...

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

0 votes

489 views

1 answer

c++ - static variable in the class declaration or definition?

I am new to C++. I have a class like this: class CodeTest { private: static const int TOTAL=100; }; ... CodeTest::TOTAL; Why is this required? See Question&Answers more detail:os...

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

0 votes

552 views

1 answer

c++ - How do I convert from LPCTSTR to std::string?

I have an LPCTSTR and want to call a function that takes a std::string parameter. What conversion do I need to do? See Question&Answers more detail:os...

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

0 votes

493 views

1 answer

c++ - Conversion from Derived** to Base**

I was reading this and unfortunately could not understand in depth why the compiler does not allow conversion ... call fireNuclearMissle()! See Question&Answers more detail:os...

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

0 votes

638 views

1 answer

c++ - Is there a clean way to prevent windows.h from creating a near & far macro?

Deep down in WinDef.h there's this relic from the segmented memory era: #define far #define near This ... Other then renaming my variables? See Question&Answers more detail:os...

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

0 votes

591 views

1 answer

c++ - Scope resolution operator being used twice

namespace libzerocoin { //Commitment class Commitment::Commitment::Commitment(const IntegerGroupParams* p, const Bignum& ... nested namespaces. See Question&Answers more detail:os...

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

0 votes

394 views

1 answer

c++ - What is the class keyword before a function argument?

Why does this code work? See the class keyword in front on the f function argument? What does it change if I add it? ... }; f(obj); return 0; } See Question&Answers more detail:os...

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

0 votes

508 views

1 answer

c++ - Using bind1st for a method that takes argument by reference

I have a struct like this: struct A { void i(int i) {} void s(string const &s) {} }; Now when I try this: ... (int &i) {} I get a similar error. See Question&Answers more detail:os...

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

0 votes

880 views

1 answer

c++ - how to use std::filesystem on gcc 8?

I have updated version of gcc, gcc --version produces the following output gcc (Ubuntu 8.1.0-5ubuntu1~16.04) 8.1. ... i built with -std=c++17 See Question&Answers more detail:os...

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

0 votes

620 views

1 answer

c++ - Load 32-bit shared library from 64-bit application?

I have a shared library that is compiled as 32-bit. Can I use it from a 64-bit application or do I need ... shared library as 64-bit as well? See Question&Answers more detail:os...

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

0 votes

550 views

1 answer

c++ - generating random enums

How do I randomly select a value for an enum type in C++? I would like to do something like this. enum ... conversion from int to an enum type. See Question&Answers more detail:os...

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

0 votes

596 views

1 answer

c++ - std::async won't spawn a new thread when return value is not stored

Consider I have lamba foo which just does some stuff and doesn't need to return anything. When I do this: std:: ... ); What am I missing here? See Question&Answers more detail:os...

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

0 votes

612 views

1 answer

c++ - When a float variable goes out of the float limits, what happens?

I remarked two things: std::numeric_limits<float>::max()+(a small number) gives: std::numeric_limits<float>::max(). std:: ... q: " << q << endl; See Question&Answers more detail:os...

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

0 votes

502 views

1 answer

c++ - Assign array to array

So I am playing around with some arrays, and I cannot figure out why this won't work. int numbers[5] = {1 ... that? What does the error mean? See Question&Answers more detail:os...

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

0 votes

593 views

1 answer

c++ - Can I use parameters for the table name in sqlite3?

I'm having some strange feeling abour sqlite3 parameters that I would like to expose to you. This is my ... name before preparing the query? See Question&Answers more detail:os...

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

0 votes

618 views

1 answer

c++ - Why must virtual base classes be constructed by the most derived class?

The following code won't compile: class A { public: A(int) {} }; class B: virtual public A { ... understand the reason behind this limitation. See Question&Answers more detail:os...

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

Categories

Just Browsing Browsing

Most popular tags