General C++ Programming

Welcome to the general programming forum in C++.com! In this forum, users can to talk about any topic related to programming in the C++ language that does not ...

[no replies]

by JUANDENT

function returning an int cannot be assigned to

I have a confusion. A function returning a value of type int cannot be assigned to - is it because that return value is an rvalue? but its type is int not int&&...

[2 replies] Last: b.value() returns an int (not addressable temporary) Correct. The ... (by seeplus)

by JUANDENT

How to include library feature macros like __cpp_lib_* if importing std only?

the library feature macros __cpp_lib_* are defined in header yvals_core.h (for visual C++) which is an implementation header and thus not meant to be included i...

[3 replies] Last: Yes I know I can #include Thanks! (by JUANDENT)

by JUANDENT

order of importing does affect the outcome!

Reading about C++ 20 modules we find the assertion that the order of importing modules does not matter, and this is always compared with #including headers. I ...

[2 replies] Last: the order of importing modules does matter if they are at least vague... (by keskiverto)

by JUANDENT

subclass does not deduce template argument in class with using std::vector<T>::vector

Hi, I have this subclass of std::vector template<typename T> class Vec : public std::vector<T> { public: using std::vector<T>::vector; // use...

[3 replies] Last: The class needs to be declared with 2 parameters like std::vector! Tha... (by JUANDENT)

by LsDefect

Unlock mutex when returning

The back-end of my application executes a command with _popen and passes the output to the front-end. void Loader::LoadBuffer(const std::string& arg) { ...

[2 replies] Last: Whoops you're right, thanks I'll make bufferLoaded atomic. As for out... (by LsDefect)

by JUANDENT

how to read a single character as with getchar but in C++?

Hi, in C one could read a single character from the keyboard with functions like getc() or getchar(). What is the equivalent in C++? streams use buffered inp...

[8 replies] Last: in C one could read a single character from the keyboard with functio... (by seeplus)

by JUANDENT

Strange arithmetic conversions

Stroustrup states in C++ Programming Language 4th edition page 271 that the result of converting an unsigned integer to a signed one of possibly larger size imp...

[5 replies] Last: This is one of the reasons why .ssize()/std::ssize was introduced to g... (by seeplus)

by JUANDENT

How to clear the buffer for istreams?

Hi, what if I want to read only one character of input from the keyboard and want to use streams? so this: char c; cin >> x; will read a charact...

[1 reply] : https://en.cppreference.com/w/cpp/io/basic_istream/ignore (by salem c)

by leo2008

c++ array negative numbers

I am trying to solve this problem, but got wrong output. Given an array of integers, write a function to move all the negative numbers to the left end of the ar...

[4 replies] Last: to move all the negative numbers to the left end of the array without... (by seeplus)

by leo2008

c++ indice 2 numbers

I solved the below problem. Can anyone tell me the best way here? Given a list of integers and a target sum, write a function to find the indices of the tw...

[4 replies] Last: Another way is to use combinations. Consider this which will find the ... (by seeplus)

by JUANDENT

What is the difference between declaring a variable auto and declaring it auto&&?

Hi, I have two variables for a general function f(): auto value = f(); auto&& other = f(); what is the difference between them?

[9 replies] Last: Why auto&& and not auto& ? I had to look this one up. && is speci... (by jonnin)

by stav

which one of these bytecode instruction designs is better?

I've been going down a bit of a rabbit hole trying to figure out the most optimal way to design a bytecode instruction class. To be clear an instruction is som...

[7 replies] Last: I don't think either of these approaches of good. To see why, consider... (by dhayden)

by Cplusc

Inconsistent Results with Different Methods

I’m facing an issue in a C++ project where two different methods for computing the same values are giving inconsistent results, despite both using the same in...

[16 replies] Last: Hi Cplusc, I hope all is well at your end :+) Sorry for an even late... (by TheIdeasMan)

by adam2016

Threading

Hello everybody, long time no post. My posts have been sporadic at best lately, but hopefully, this one will gain some traction and be helpful to many who find ...

[18 replies] Last: Not that it really matters your link lists different authors for the ... (by seeplus)

by ElusiveTau

Why are there multiple multithreading frameworks?

In my learning, I've come across several multi-threading frameworks. I know the language didn't officially provide thread support until C++11 and that some thre...

[8 replies] Last: PS. There's also: Intel Threading Building Blocks https://www.intel.co... (by seeplus)

by helios

About full-duplex sockets

Sockets are supposed to be full-duplex, right? So the endpoints should be able to send and receive literally at the same time. But how do you handle that at the...

[1 reply] : I'm not even sure what API you are using here 🤔 But, if we are tal... (by kigar64551)

by JUANDENT

Mismatch overload problem

Why does s have the value false? template<typename T> char test_have_range(decltype(&T::begin), decltype(&T::end)); template<typename T> short test_hav...

[1 reply] : #ifndef DUTHOMHAS_IS_ITERABLE_HPP #define DUTHOMHAS_IS_ITERABLE_HPP ... (by Duthomhas)

by JUANDENT

How to test if a type T has a begin<T> defined

I have a SFINAE context where I have the following: struct have_sort { char c; }; struct have_range { char c ; }; struct have_none { char c ; }; ...

[no replies]

by JUANDENT

why testing for member pointer determines the template type is a class?

why does this code determine if the type is a class: template<typename T> class is_class { template<typename C> static char test(int C::*); template<typena...

[4 replies] Last: Thanks!! (by JUANDENT)

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