Questions tagged [c++]
Questions about C++, a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language.
-2
votes
1answer
71 views
What's the best design pattern approach for introducing optional feature to current code base?
I had a class hierarchy with several classes that interact with each other. After introducing new feature that is optional (but it depends on external libraries) I have the following code (just ...
1
vote
0answers
64 views
Designing a multithreaded TCP/UDP server for audio sharing
As briefly introduced in the question title, I am trying to design and implement a server application able to let clients share audio contents between themselves. In order to achieve that, I decided ...
-3
votes
1answer
95 views
Which is the best pattern or solution for this problem?
Given the following class:
class S
{
...
private:
void Action1();
void Action2();
.
.
.
void ActionN();
}
The Action functions are related, which are called in ...
-4
votes
1answer
59 views
Why is wchar_t in C++ implemented as a new data type? [on hold]
I am learning C/C++ and have come across the type wchar_t, which appears to be 2 byte long char. So my question is why did C++ add a new type, when it could have just added the ability to apply the ...
-4
votes
0answers
32 views
extract function calls and arguments [on hold]
I have a text written in c++ .
I need to extract from it functions calls and their arguments.
I used Antlr v 4 to write a small program but I just could get function definitions.
my attempt
My ...
1
vote
1answer
47 views
Unit testing abstract classes with Google mock (gmock/gtest) (C++)
I want to test an abstract class with:
Pure virtual methods that should be overridden in sub-classes
Non-pure virtual methods that use the pure virtual methods (as opposed to this question)
class Fu
...
-2
votes
1answer
42 views
Using static member methods to check for object being NULL
Is it a good practice to use the static member methods to check if an object of a class is NULL or not. The object would be sent through the parameters offcourse.
Something like,
#include <...
5
votes
1answer
212 views
How common are destructors in modern c++ code?
In the standard c++ library, all containers and all input/output streams have their own constructors and destructors, that handle all the relevant resource acquisition and release.
So for most tasks ...
-1
votes
0answers
27 views
What happens to a raw pointer member of a class foo smart pointer when the smart pointer is destroyed? [on hold]
Say we have a smart pointer (std::unique_ptr) of class foo. This class has a raw pointer as a member.
The program is executed and smart pointer foo carries out its intended functionality.
If there'...
-2
votes
0answers
53 views
C++ code generation [on hold]
I need to generate C++ code (headers and implementations).
I would like to do it in C++ or C#.
I can think of:
Simply appending to string or writing to file directly
Template-based approach (using ...
-2
votes
0answers
43 views
How to programmatically modify code in a Visual Studio C++ project [on hold]
Let's say there's a set of actions I want to repeat every time I make a specific change to a codebase, for example I want to globally forward declare a newly created entity type for a video game, or I ...
-2
votes
0answers
44 views
How to auto populate 4 PDF's per truck load? [closed]
I have lets say 40 trucks of meat come to my Wearhouse every day, each truckload requires us to fill out 4 different PDF's that go 4 different places. The information is basically the same on each ...
0
votes
0answers
77 views
Base class with bool flag to imitate virtual constructor
I am using bool flag to call base class function when needed to imitate virtual constructor. I am using this way for inheritance purpose. I have a Base class constructor with int and bool. The bool ...
-4
votes
0answers
37 views
I Don't understand this C++ run-time behaviour [migrated]
int main()
{
cout<< "Please enter your first name (followed by 'enter'):\n";
string first_name; // first_name is a variable of type String
cin >> first_name; // read ...
6
votes
1answer
174 views
How can I reduce the amount of storage needed for a gravitational n-body simulation?
I am currently attempting to create a gravitational n-body simulation using a modified Barnes-Hut algorithm, to be more amicable to GPU computation. This is primarily as a learning project. My goal is ...
1
vote
0answers
60 views
Unit testing C++ in XCode
I'm working on a plugin for some drafting software. The plugin takes the form of a dynamically loaded mach-o bundle.
The software vendor provides a template plugin in the form of an XCode project.
...
1
vote
1answer
96 views
One process using std::thread, 2 physical CPUs, 4 cores each, parallelism level?
Suppose I have a one C++ process, and I want this process to run eight threads in parallel.
And suppose that:
I have a computer with two (2) physical CPUs.
Each CPU has four (4) cores, so that's 4x2 ...
2
votes
3answers
206 views
In c++, is there a way inside a function block, to execute cleanup code after the value has been returned?
Backstory (You can skip)
I am building an API for managing Files and Directories in a consistent manner across a project. This is for deduplication and consistency when performing a task, and in this ...
0
votes
1answer
60 views
Avoid numerous dynamic_cast_ptr in the API design of polymorphic types
I am trying to design a geometric intersection API. Below is the code to represent geometric elements.
#include <iostream>
#include <memory>
// Since I did not write the Shape class I ...
8
votes
4answers
375 views
C++ Iterator, Why is there no Iterator base class all iterators inherit from
I am learning for an exam and I have a question which I am struggling to give and answer for.
Why does no iterator base class exist all other iterators inherit from?
My guess my teacher is ...
0
votes
1answer
87 views
Difference between a strongly typed language and a weakly typed language with type annotations from the developer's point of view?
I understand that there are major technical differences between how a strongly typed language is compiled and how a type annotated language is compiled/transpiled.
But as a developer writing in a ...
1
vote
2answers
96 views
Pattern for composing streaming operations without threads?
I'm working on a library that lets me write operation on an input "stream" of data (I don't call them that, but it's a potentially unbounded input regardless, think data coming from a socket).
I ...
1
vote
2answers
219 views
Why is the whole Hadoop ecosystem written in Java?
Developing Big Data processing pipelines and storage, you probably come across software which is more or less a part of the Hadoop ecosystem. Be it Hadoop itself, Spark/Flink, HBase, Kafka, Accumulo, ...
0
votes
4answers
113 views
Is it better to use the linker to compile multiple C++ files or better to include them as a header file
Assume we have two files
a.cc
#include <iostream>
int timesTwo(int in);
int main(){
std::cout << timesTwo(5) << std::endl;
return 0;
}
b.cc
int timesTwo(int in){
return in*2;...
6
votes
3answers
422 views
Why do you want to avoid flushing stdout?
I stumbled upon a question in Codereview, and in one answer the feedback was to avoid std::endl because it flushes the stream. The full quote is:
I'd advise avoiding std::endl in general. Along ...
1
vote
1answer
93 views
How many bytes is a long in a 64 bit machine [closed]
I have compiled the following simple c++ code:
#include <iostream>
int main(){
int a = 5;
int b = 6;
long c = 7;
int d = 8;
return 0;
}
and here is the assembly:
pushq %rbp
....
16
votes
3answers
1k views
How does GDB pause an execution
As you may know, we can use GDB and set breakpoints on our code to pause execution for debugging.
My questions is, how does GDB pause a process and let you view the content of registers using i r for ...
-1
votes
1answer
112 views
What is the C++ equivalent of a logging facade in Java?
I'm currently writing a library in C++ and was wondering if I should log from within it. Googling the issue I came across this question but it makes reference to a logging facade. Is there anything ...
2
votes
1answer
130 views
How to optimize reusing a large std::unordered_map as a temporary in a frequently called function?
Simplified question with a working example: I want to reuse a std::unordered_map (let's call it umap) multiple times, similar to the following dummy code (which does not do anything meaningful). How ...
0
votes
0answers
50 views
Linear “steps” of operations considered a state machine?
I have a set of tasks I perform to complete some larger operation. These tasks must be executed in linear order, and you cannot proceed onto the next task until the previous completes. For the most ...
1
vote
2answers
77 views
Analyzing stack and heap using GDB and C++
I have a simple c++ code as the following:
#include <iostream>
int main() {
int a = 5;
int *b = (int *) malloc(40);
return 0;
}
Setting a breakpoint using GDB on line 5 and ...
0
votes
2answers
202 views
Usage of the word “override” in C++ and it's virtual functions
I know that the following function is a virtual function and needs to be overridden when extended by another class:
virtual int getAge()=0;
What i don't understand is the following syntax I have ...
22
votes
6answers
7k views
Why is C/C++ main argv declared as “char* argv[]” rather than just “char* argv”?
Why is argv declared as "a pointer to pointer to the first index of the array", rather than just being "a pointer to the first index of array" (char* argv)?
Why is the notion of "pointer to pointer" ...
1
vote
0answers
15 views
Save data from multiple Qt components scattered around multiple QML files
I would like to save the current "value" property of several components (e.g. a Slider) as a configuration profile when the user clicks on the Save button in my application. However, the Save button ...
1
vote
2answers
248 views
Notify Millions of subscribers at the same time(or with min. delay) in C++?
I'm working on a problem, in which i have some real time weather information of different cities through out the world. I'm exposing subscribe function to interested people/clients, with input:- ...
2
votes
3answers
113 views
filesystem::path vs. optional<filesystem::path> as argument to function
Sometime ago in a code-review (C++) I suggested to change the input argument from Path type to Optional<Path>, where the function has specific logic for unset path. It looks for me intuitively ...
0
votes
2answers
132 views
Force field initialize not by constructor in c++
My parent class has a vector field
I want to force child classes to push in that vector as many as items they have. At least one item
example:
class Options {
protected:
vector<...
-2
votes
1answer
60 views
How to identify test cases?
I wrote a small INI file parser as a library which I want to use in a bigger project. Following good practice I decided I should write test cases, too. But I fail to find a good start.
The library is ...
1
vote
2answers
146 views
Is it good practice to statically link libstdc++ and/or libgcc when creating distributable binaries for Linux?
Context: I have an open source project which uses JNI. While it's possible to build it yourself, I expect most users will use standard Java tools like Maven, Gradle, or SBT to download the JAR, which ...
2
votes
2answers
82 views
Convert template type to derived type when calling a function?
Apologies if the title is incorrect, I couldn't think of better wording. I have the following code
template <class E>
void ResolveEntityHit(E& entity, Projectile& projectile) {
...
1
vote
1answer
92 views
Architecture of iterating over polymorphic types
I have a base type of Entity, and multiple implementations, Enemy, Bunker, Projectile
I have separated these entities into their own containers so I can pass them to different classes to perform ...
-3
votes
1answer
155 views
Is my algorithm for determining whether a ipv4 is public or private correct? [closed]
I have just created a function which checks whether a ipv4 is public or not. I have not heavily tested it yet since it is kind of practically impossible to do so (because I do not know where to start)....
4
votes
2answers
231 views
Game Playing AI - Strategy to overcome the transposition table taking up too much memory?
I've made an engine that plays Connect Four using the standard search algorithms (minimax, alpha-beta pruning, iterative deepening, etc). I've implemented a transposition table so that the engine can ...
-3
votes
2answers
81 views
Is it a bad practice to include stdlib header file from a header file corresponding to the source file that needs that stdlib header?
If a file foo.cpp already includes foo.h, and foo.cpp requires some types from (for example, string.h), which is better, to include string.h in foo.cpp, or in foo.h ?
For example, Guideline#9 in this ...
8
votes
2answers
234 views
Why does the base class need to have a virtual destructor here if the derived class allocates no raw dynamic memory?
The following code causes a memory leak:
#include <iostream>
#include <memory>
#include <vector>
using namespace std;
class base
{
void virtual initialize_vector() = 0;
};
...
-1
votes
2answers
112 views
How to represent a directory structure in a binary tree?
I was just thinking about implementing a binary tree with its root pointing to the parent folder and then the children pointing to subdirs nested within to store a directory structure in a binary tree....
1
vote
1answer
76 views
How to efficiently access public static variables/methods of the correct derived class?
I have an arbitrary number of derived classes all inheriting from the same base class. These derived classes all have the same static variables and static methods, although the implementations may ...
0
votes
1answer
112 views
Is there a way to use and ignore blocks of code, caused by events during runtime?
I'm working in C++14 and trying to figure out a way to put two classes (with the same name) inside the same header file. In this scenario one class would always be ignored as a result of something ...
5
votes
2answers
148 views
How to track C++ class traits?
As a fan of regular types and value semantics, I'm keen on classes becoming more regular and being non-polymorphic. As a fan of non-throwing operations, I'm keen on operations being noexcept. I also ...
1
vote
1answer
141 views
How to pass integers between two C++ program using IPC
How do you pass a integer between two process. I'm new to IPC and using pipes I know how to transfer the string between two process. But how can I pass a numbers like that?. I can do this with the ...
