General C++ Programming - C++ Forum

What is the reason for the explicit template specification order / special status of first argument?

I started experimenting with the C++20 feature of concepts and was very pleased when I realized that it is possible to partially explicitly provide template arg...

[1 reply] : this was already discussed in http://cplusplus.com/forum/general/2744... (by Cubbi)

by Viktor123

I am having trouble with this problem. I am stuck.

 You will be using a data file called “christmas.dat”. To copy the data file to your directory, do cp /export/home/public/may/christmas.dat christmas....

[1 reply] : I am having trouble with this problem. I am stuck. Stuck at what po... (by seeplus)

by Morriss1

Linked list removing problem [repost from r cplusplus]

Hello, here I have a program which takes in the head of a linked list and the value that I want the node removed. It successfully removes and returns the head i...

[2 replies] Last: Using a prev pointer: for (Node *current=head, *prev=nullptr; cur... (by dhayden)

by dman25

Create new object with std::async

Is there a way to call a constructor and create a new object with std::async?

[3 replies] Last: Oh yeah. Or you could just return it. (by Repeater)

by Cambalinho

3D camera: i need a correction on camera size

how can i use the camera size for the window size: camera1.size.Height = Me.ScaleHeight + 100 camera1.size.Width = Me.ScaleWidth camera1.Position.X ...

[16 replies] Last: I don't have VB. But you can easily check your code in two ways: 1. T... (by againtry)

by BZKN

calculate size of the data from function arguments

Hi, I am struggling to understand how to calculate the size of the data in a function given its function arguments. For example below is the function foo ...

[1 reply] : It passes 2 pointers and 2 ints, therefore the size of the data passed... (by seeplus)

by hakmaabdul

linking node at the end of the list

Hi all, I tried to link a new node(NewNode) at the end of the list but it is not executing the last statement (last->next = NewNode). Could you guys help me to ...

[2 replies] Last: Thank you for the information, it's really helpful. Now, I'm able to l... (by hakmaabdul)

by Kennethh

Why is __cplusplus defined within extern “C”

Within extern "C" { } the macro __cplusplus is still defined. When I want to include the C version of mpi.h in the header of my library which is dynamically loa...

[1 reply] : You forgot to extern "C" the definition of library_do(), thus the func... (by helios)

by junweinehc

Is this name collision?

The error was "no instance of overloaded function "people::people" matches the specified type" on the first line of code of my C++ file. People::people... I inc...

[5 replies] Last: This compiles and runs OK as 1 file: #include <string> #include <io... (by seeplus)

by Bapt

Create an histogram from datas vector

Hi Everybody, I would like to print a histogram from datas vector. My vector is composed of a 256 index and each index counts the number of gray scale le...

[8 replies] Last: Thanks for all !! (by Bapt)

by java982

Help with Implementing a class please

I need to write an application, which reads two times and finds out which time is later. After that it calculates the time difference between these times ...

[2 replies] Last: Double posting: http://www.cplusplus.com/forum/windows/274453/ (by George P)

by JUANDENT

C++20: concept definition parameters seems inverted

Hi, This next concept: template <class T, class U> concept SubClass = std::is_base_of<U, T>::value; used in this context: template<SubCla...

[1 reply] : Looks like that "SubClass" was someone's version of the standard libra... (by Cubbi)

by neonblue00700

TLE

Hello, can somebody help me, I wrote a code that calculates a^b and then finds how many digits does that number have, but I have a problem when I put 2 numbers ...

[4 replies] Last: that too. but you fixed that already :) If the OP is going to be pla... (by jonnin)

by grooviqw

std:: or using namespace std

Why so many people use std:: instead of just writing using namespace std at the top?

[6 replies] Last: There are a lot of names in the std:: namespace. If put using namespac... (by dhayden)

by Mante

What do I need to know when mixing C and C++ code?

// C++ code extern "C" void f(int); // one way extern "C" { // another way int g(double); double h(); }; void code(int i, do...

[1 reply] : https://isocpp.org/wiki/faq/mixing-c-and-cpp (by salem c)

by msikora

Weird compiler behavior

Recently I have stumbled across a piece of code, that puzzles me, because different compilers compile it in a different way: #include <iostream> using names...

[2 replies] Last: The problem is one of evaluation order , not operator precedence: it ... (by mbozzi)

by junweinehc

Beginner Level Pointer

#include <stdio.h> #include <cmath> void update(int *a,int *b) { // Complete this function *a+=*b; *b=abs(*a-2**b); } To calculate b...

[6 replies] Last: @furry guy Suppose be C++. I was doing some C++ practices for some r... (by junweinehc)

by grooviqw

replacing a character in a string

Hi How can i replace a character from a introduced string? let's say i introduce "aabcf" i want to replace all a leters with b , so i introduce from the keyboar...

[9 replies] Last: OK #include <string> #include <iostream> #include <map> int main()... (by seeplus)

by neonblue00700

Reapating numbers

Hello, I got a task to do in my university studies, and I don't have any idea how to do it,may somebody help me ? So the task is to make an array and make a pro...

[5 replies] Last: That's one part of the answer - how about the rest? In this sequence ... (by lastchance)

by vish09

Threads accessing same buffer

I have a big buffer that I want to share between threads, each thread will always be reading from different parts of the buffer (never from the same part), so s...

[3 replies] Last: Thanks for clearing my doubts. (by vish09)

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General C++ Programming - November 2020