CPP QUESTIONS

Find critical edges of an MST: possible with modified Prim's algorithm?

this one helps. This problem is easier than the problem of sensitivity analysis of minimum spanning trees, which is to determine how much each tree/nontree edge can increase/decrease in weight before the minimum spanning tree changes. The best known

TAG : cpp

Date : November 22 2020, 10:40 AM , By : jinglebell

Converting wostringstream to wchar_t* Garbles Values

will help you The wostringstream::str() method returns a std::wstring by value. You are not assigning that to anything, so its lifetime is temporary and ends when the expression is finished. You are calling std::wstring::c_str() to save a pointer to

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955639

Causing segfault in program doesn't get caught by signal handler

seems to work fine So the explanation of this is that RTEMS does not handle signals the way that I thought it does. There are some POSIX signals which are really exceptions at the hardware level. for eg. SIGSEGV, SIGBUS, and SIGFPE. The exact semanti

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955615

Undefined symbol: _ZN7QString13toUtf8_helperERKS_ at runtime

it fixes the issue qmake/cmake is the way to go. But it is interesting to see how come linker succeeds and then during run, we get an undefined reference( not an unmatched dll case ). Especially since there is no preprocessor guard for toUtf8_helper

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955560

proper usage of C dummy functions replacement in different environment

fixed the issue. Will look into that further I am trying to add test functions in a suite on both windows and linux machines. On linux machines i want the real functions to be added and on windows machine i want the dummy UnsupportedFunction to be ad

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955556

How do you save images of detected objects in OpenCV?

This might help you The function call that detects the face will most probably contain a boundingRectangle parameter of type vector. Use the data present in it to select the Region of Interest(ROI) if a face is detected. This selected ROI can then be

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955555

See if length between two equal numbers in deque is even

I think the issue was by ths following , I have a deque and I want to find if the number of ints between two equal numbers is even. For example:7,13,4,6,4,13,8,10 should be false and 1,3,5,3,4,8,7,9,6,5,7 should be true. I think my program is correct

TAG : cpp

Date : November 22 2020, 10:40 AM , By : DeltaFlight

Random real in [0..1[ using Mersenne Twister

I think the issue was by ths following , This happens because the return value of newr() and newr.max() are integers and the value returned by newr() is smaller than newr.mar(). The result of the division is a zero integer which is then converted to

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955427

Writing the contents of a map through operator overloading

seems to work fine Your operator

TAG : cpp

Date : November 22 2020, 10:40 AM , By : user2955396

Defined operator works in main() but doesn't work in class

it helps some times It does not work in Plane since the Punkt objects are const and the operator- function is a non-const member function.You should make operator- a const member function.

TAG : cpp

Date : November 22 2020, 10:40 AM , By : nitrazepam

Can a throw or delete expression ever be dependent?

it helps some times Let's go back to when typename is required. §14.6 [temp.res]/p3, all quotes are from N4140:

TAG : cpp

Date : November 22 2020, 10:38 AM , By : user2955289

C++ finding the (largest) index of the largest element in an array

I wish this helpful for you I have an array of values and a technique for finding the index of the largest element in an array. , In a for loop add an if statement. Something like...

TAG : cpp

Date : November 22 2020, 10:38 AM , By : user2955178

Can sizeof nested twice ever be a dependent expression?

fixed the issue. Will look into that further I noticed that gcc 5.0 rejects the following code, while clang 3.6 accepts it. , I'm using a post-N4296 draft.

TAG : cpp

Date : November 22 2020, 10:38 AM , By : KarthikaEswaran

Creation of objects from a string (C++)

I wish this helpful for you Ok, so you can't do what you're trying to do directly in C++. There is a bit of a workaround though:You can create a map, let's call it myCities:

TAG : cpp

Date : November 22 2020, 10:38 AM , By : user2955124

OpenCV: extractor->descriptorSize() - Segfault

I wish this help you I found out that the nonfree module of OpenCV was not installed. After installation I included the nonfree library include and then called cv::initModule_nonfree();. The problem is solved.

TAG : cpp

Date : November 22 2020, 10:33 AM , By : user2955060

C++ generic iterator

like below fixes the issue You can simply use traits to remove the T type completely, allowing it to be determined automatically:

TAG : cpp

Date : November 22 2020, 10:33 AM , By : user2955034

Why HANDLE created by 'CreateEvent' isn't valid in another process?

it should still fix some issue Handles are kinda like pointers in that they're usually process-specific. It takes special actions (like using DuplicateHandle) to share them.Depending on the situation, it might just be easier to name the object and th

TAG : cpp

Date : November 22 2020, 10:33 AM , By : Jessica Hawkins

Assistance with a Memory Allocation Error in c++, linux using g++

it should still fix some issue I've searched for others with similar problem's to mine, but they all have much different code than I. , Take another look at this:

TAG : cpp

Date : November 22 2020, 10:33 AM , By : stanicmail

Returning by reference a member of a destroyed local variable

To fix this issue Since foo returns its return value by value (not by reference), foo makes a copy of the vector to return. It copies from the reference it got back from getNumbers as part of the return before it destroys the local variable a, so at

TAG : cpp

Date : November 22 2020, 10:33 AM , By : FatalError

Opengl: how do I affect the lighting on a textured plane?

like below fixes the issue There are at least two problems that prevent you from getting good lighting. The first one should be easy to solve. The second one goes deeper.Texture combination setting

TAG : cpp

Date : November 22 2020, 10:33 AM , By : user2954963

VS2013 and Unicode literals give warnings

will be helpful for those in need There's only one way I can repro this, saving the text to a file encoded in utf8 without a BOM. The compiler will guess at the system default codepage and trip over the double bytes in the utf8 codes produced by the

TAG : cpp

Date : November 22 2020, 10:33 AM , By : user2954962

Define macro error: expected primary-exception before 'asm'

this will help This code is supposed to provide an assert function, for debugging only, where it automatically creates a breakpoint if the assert fails (not the full code): , You're trying to use a statement as an expression. Try something like

TAG : cpp

Date : November 22 2020, 10:33 AM , By : user2954948

Multi-property sort is inverting elements

hope this fix your issue Your comparison functions are both broken. Neither implements the necessary strict weak ordering that std::stable_sort requires. Specifically, Irreflexivity: f(x, x) must be false. Antisymmetry : f(x, y) implies !f(y, x)

TAG : cpp

Date : November 22 2020, 10:33 AM , By : Yuval Dolev

'template argument deduction/substitution failed' after addition of an argument

This might help you Since clang++ shows a different (and strange) behaviour in this case, I'm not entirely sure of this answer. However, I think I can explain what's going on when using g++.Let's take a look at the following example:

TAG : cpp

Date : November 22 2020, 10:33 AM , By : sdev

copy constructor for two dimensional vector

it fixes the issue I want to write a copy constructor for two dimensional vector

TAG : cpp

Date : November 22 2020, 10:33 AM , By : user2954811

How can I control static analyzed compiler error messages with templated libraries?

it should still fix some issue Both gcc and clang support Diagnostic Pragmas which will allow you to ignore specific diagnostic messages for a section of code. For example to disable -Wunused-variable like so:

TAG : cpp

Date : November 22 2020, 10:31 AM , By : user2954716

Source code is calling wrong template class function in c++, how to fix?

help you fix your problem The type of names is char const*[2]; after conversion to a pointer, it becomes char const**, not char*. You can't call the non-template function, because there is no conversion from char const** to char*.Also, of course, the

TAG : cpp

Date : November 22 2020, 10:31 AM , By : user2954700

Why does a struct have to be in the same namespace as a template class in order to compile?

around this issue It's not about the struct.It's about bind and Argument Dependent Lookup.

TAG : cpp

Date : November 22 2020, 10:31 AM , By : user2954663

Why is template type deduction failing here?

Hope that helps Template arguments for types cannot be deduced, period. This is because type specializations can provide a completely different set of members, so until you know the type's template arguments you don't even know what constructors are

TAG : cpp

Date : November 22 2020, 10:31 AM , By : user2954610

Program Efficiency & Readability

I wish this help you Inspect the assembly of an optimizing compiler to reach a conclusionSee e.g. this on godbolt.com ¹

TAG : cpp

Date : November 22 2020, 10:31 AM , By : Charles DeLone

C++ console input blocks so i can't kill thread

should help you out What you could do is using futures to allow the user to input something with a time limit. You can then insert this code into your main loop

TAG : cpp

Date : November 22 2020, 01:01 AM , By : Koukouttou

polarToCart and cartToPolar functions in opencv

To fix this issue if you're using opencv3, you probably want linearPolar:note, that for both versions, you need a seperate src and dst image (does not work inplace)

TAG : cpp

Date : November 22 2020, 01:01 AM , By : jschwuchow

Remove spaces from char-array by using a function with a pointer argument

I think the issue was by ths following , The call to removeSpaces has no affect because you are creating a temporary buffer in the function and copying the string into that while applying the transformation. You can fix this by removing the temporary

TAG : cpp

Date : November 22 2020, 01:01 AM , By : Tom

Input numbers until -1 is inputed

I think the issue was by ths following , The problem is that after a complete line has been entered n is never reset to a default value and still contains -1. On the next iteration this causes the inner while loop to be skipped and temp.front() to be

TAG : cpp

Date : November 22 2020, 01:01 AM , By : user2954229

Why isn't RVO / NRVO always applied?

Any of those help Obviously, when an lvalue is returned by value, there is no way to not do a copy. So, let's consider only local variables. A simple reason applying to local variables is that often it is unclear which object is to be returned. Consi

TAG : cpp

Date : November 22 2020, 01:01 AM , By : user2954185

Check if type can be an argument to boost::lexical_cast<string>

hop of those help? Your expression is not sufficient, as the lexical_cast function template takes everything and only reports errors via an internal static_assert. Instead test whether inserting the object into an std::ostream is valid:

TAG : cpp

Date : November 22 2020, 01:01 AM , By : AĦmệd Kặŝệm

Hide sh: -c error messages when calling “system” in c++ Linux

wish help you to fix your issue Think that system forks a process and then executes the command you've provided. The new process inherits the descriptor from its parent and that new process is writing in its standard error.So, this code snippet may d

TAG : cpp

Date : November 21 2020, 07:31 AM , By : user2954056

Qt5 SSL support

I think the issue was by ths following , I am about to make a web api request: , Most likely you have to install new version of OpenSSL.

TAG : cpp

Date : November 21 2020, 07:31 AM , By : user2954029

Inheritance of composition relationship in C++

I hope this helps . I quite often confront myself to this problem. Let's say I have these classes: , You could just have A have a protected constructor that takes a B*:

TAG : cpp

Date : November 21 2020, 07:31 AM , By : user2954012

How to use System functions in c++ on linux

I think the issue was by ths following , You use system just like any other function. The only caveat is that the command you are executing must be available on the system your application is running on and within the same context your application is

TAG : cpp

Date : November 21 2020, 07:31 AM , By : user2953997

what is the reason of this error?

I wish this help you The problem is that the class definitions are not visible to the compiler when you try to access members of an instance. Although you have provided forward declarations for the classes this is not enough. In the .cpp and .h files

TAG : cpp

Date : November 21 2020, 07:31 AM , By : Magdalena

Strange behavior in C++, cout statement is required to prevent app crash?

seems to work fine The problem is that you never allocate memory for buffer in string_to_ints. Since this is undefined behavior anything can happen, includiing appearing to work when a cout is in place and not working when the cout is removed.The sim

TAG : cpp

Date : November 21 2020, 07:31 AM , By : safaa

Why isn't abs constexpr?

seems to work fine I can't give a good reason for why abs couldn't be constexpr and apparently neither can gcc. When I use gcc 4.9.2 with this program:

TAG : cpp

Date : November 21 2020, 07:31 AM , By : Imelda Clarke

C++ Can't increment a variable

I wish this help you I'm working on an Animation class for a small game engine, and for some reason the frame counter does not want to increment, it keeps stuck at 0 or 1.

TAG : cpp

Date : November 21 2020, 07:31 AM , By : user2953825

C++ substring seems to be pointing at wrong spot

help you fix your problem Short Answer Your file is encoded in UTF-8 and it has a Byte Order Mark at the beginning.

TAG : cpp

Date : November 21 2020, 01:01 AM , By : mexicanace

How change default color of text in wxRitchTextCtrl

around this issue How change color default of text? wxRitchTextCtrl , I would try this:

TAG : cpp

Date : November 21 2020, 01:01 AM , By : user2953743

static variable vs stack variable: thread safety vs stack size?

With these it helps It's not just a matter of initialization. A static variable, even one defined within a function, is a single instance that's shared by all calls to that function — even calls in different threads. If you use a static variable as a

TAG : cpp

Date : November 21 2020, 01:01 AM , By : Dee Dubs

Transforming trees in C++

Any of those help One way to solve the problem on having to dispatch on unique_ptr is to go back to passing around pointers the way you do in your visitor, but changing the return type to Node*, like this:

TAG : cpp

Date : November 21 2020, 01:01 AM , By : Mihail Rodrigo Marti

Make a C++ initializer automatically detect union member?

this will help OK, the standard still says that brace-initializing a union initializes only the first member. I suppose this puts this question more in the "Wouldn't it be nice if...?" category. , Update In my introduction I mentioned:

TAG : cpp

Date : November 21 2020, 01:01 AM , By : user2953721

c++ headers between projects

Any of those help You can as long as you don't use templates in project A that depends on LLVM headers. You can always forward declarate the types you are using in project A headers and include the actual headers in the cpp files.Say there is a type

TAG : cpp

Date : November 21 2020, 01:01 AM , By : Theresa Pablos

Passing pointers as a parameter in C++ rather than using this pointer

wish help you to fix your issue First thing to get straight: a non-static member function is essentially just like any other function, but has an implicit parameter called this which is a pointer to the object that the member function was called on.

TAG : cpp

Date : November 21 2020, 01:01 AM , By : user2953619

How to initialize the dynamic array of chars with a string literal in C++?

may help you . I want to do the following: , Here's a solution based on std::array:

TAG : cpp

Date : November 21 2020, 01:01 AM , By : user2953598

Prevent breaking encapsulation

like below fixes the issue As you might have seen from the other answers and comments, the answer is: It depends.In fact, it depends mainly on the usecases where your class is used. Let's stick first to the example given in the question, the comparis

TAG : cpp

Date : November 21 2020, 01:01 AM , By : user2953576

How to add color palette to BITMAPINFO

Does that help I modified the function and didn't use BITMAPINFO at all. I used RGBQUAD to write the color palette instead. Here's the solution:

TAG : cpp

Date : November 21 2020, 01:01 AM , By : aswderf sdfwerf

How to handle different header file location on different Linux distributions?

hope this fix your issue In my code I use a header file which unfortunately has a different location under different Linux distributions. , Keep the simpler include

TAG : cpp

Date : November 20 2020, 01:01 AM , By : matt3948

Making a particular bit "0" in C++

seems to work fine I'm new at programming. Recently i came across a problem in which i have to make a particular bit 0 of a number. , Just use :

TAG : cpp

Date : November 20 2020, 01:01 AM , By : user2953312

C++ spliting string by delimiters and keeping the delimiters in result

fixed the issue. Will look into that further You could build your solution on top of the example for regex_iterator. If, for example, you know your delimiters are comma, period, semicolon, and hyphen, you could use a regex that captures either a deli

TAG : cpp

Date : November 20 2020, 01:01 AM , By : user2953253

How does Priority queue compare and store the values during the push operation?

Hope that helps A priority queue is commonly implemented as a perfectly balanced heap structure. The heap can be seen as a binary tree with the only requirement that the priority of the root is higher(smaller value for your comparator) than its child

TAG : cpp

Date : November 19 2020, 03:59 PM , By : William Neel

Copy tables between sqlite databases, qt, causes error

To fix the issue you can do I want to write the contents of my SQlite database on user click to another SQlite database. For this I am trying to make connections to two databases and do select query from one db and in transaction do insert query to a

TAG : cpp

Date : November 19 2020, 03:59 PM , By : fernando zacarias

Dealing with ambiguous declarations in C++

I wish this help you As already mentioned, you can wrap your function declaration with another namespace or you can just use the std::pair class and avoid reinventing the wheel. Also note that the std::pair class allows you to create pairs of generic

TAG : cpp

Date : November 19 2020, 03:59 PM , By : user2953031