Server does not read from clients - c++

Question

Gist of the program: The server creates n client processes. On the client, the user enters a character string that is sent to the server. On the server, the string is processed as follows: the frequency of occurrence of vowels and numbers in the entered string is calculated. This information is then sent to the client.
Two programs (server and clients) were based on console editions(They works perfectly). When I add QT support to server, console clients and gui server works fine, but when i add gui to client - it stop working and i don't know what to do.
I guess the problem is not even named pipes, but clumsy code in terms of Qt (in client). The client outputs that a connection to the server has been established, and the server indicates that it cannot read a string from the pipe.
Server can create n gui clients and then, when i try to write string to client, client closes.
Code of the client:
gui_pipe_client.h:
#pragma once
#include <LotsOfLibraries...>
class Window : public QWidget {
Q_OBJECT // этот макрос должен включаться в классы, которые объявляют свои собственные сигналы и слоты
private:
HANDLE. m_hndlNP;
public:
Window(QWidget *parent = 0, HANDLE m_hndlNP = NULL);
private slots:
int OnSend();
private:
QLabel *lbl;
QLineEdit *textfield;
QPushButton *button_send;
};
gui_pipe_client.cpp:
#include "gui_pipe_client.h"
#include <QGridLayout>
#include <thread> //!NEW!
using namespace std;
#define PIPE_TIMEOUT 5000
#define BUFSIZE 4096
Window::Window(QWidget *parent, HANDLE hndlNP)
: QWidget(parent), m_hndlNP(hndlNP){
QLineEdit *textfield = new QLineEdit(this);
textfield->setPlaceholderText("Enter string...");
QPushButton *button_send = new QPushButton("Send", this);
QPushButton *button_quit = new QPushButton("Quit", this);
lbl = new QLabel("kjiqofj13fjio2;3fjl;3jiofj2l3;fij3;fioj423j;fj32jf;o3f", this);
lbl->setWordWrap(true);
QGridLayout *grid = new QGridLayout(this);
grid->addWidget(textfield, 0, 0);
grid->addWidget(button_send, 1, 0);
grid->addWidget(button_quit, 2, 0);
grid->addWidget(lbl, 3, 0);
setLayout(grid);
connect(button_send, &QPushButton::clicked, this, &Window::OnSend); // привязка сигнала и слота
connect(button_quit, &QPushButton::clicked, qApp, &QApplication::quit); // signal - slot
}
int Window::OnSend() {
button_send->setEnabled(false);
char text[1024];
const QByteArray stringData = textfield->text().toUtf8();
//char text[100];
text[qMin(1023,stringData.size())]='\0';
std::copy(stringData.constBegin(),stringData.constBegin()+qMin(1023,stringData.size()),text);
printf("%s", text);
char answer[1024];
DWORD read_bytes;
DWORD written_bytes;
if (WriteFile(m_hndlNP, text, 1024, &written_bytes, NULL)) {
if (!ReadFile(m_hndlNP, answer, 1024, &read_bytes, NULL)) {
//printf("ReadFile failed with %d.\n", GetLastError());
system("pause"); // TEMPORARY
//return EXIT_FAILURE;
}
}
else {
printf("WriteFile failed with %d.\n", GetLastError());
system("pause"); // TEMPORARY
//return EXIT_FAILURE;
}
//cout << "Writting and reading was successful\n";
lbl->setText((QString) (answer));
// ***CLOSING PIPE CONNECTION***
CloseHandle(m_hndlNP);
//QApplication::quit();
}
main.cpp:
#include "gui_pipe_client.h"
using namespace std;
int main(int argc, char *argv[]) {
cout << "Client is launched\n";
HANDLE hndlNP = CreateFile(
TEXT("\\\\.\\pipe\\os_lab4_pipe"),
GENERIC_READ | GENERIC_WRITE,
NULL, // Prevents other processes from opening a file or device
NULL, // cannot be inherited by any child processes
OPEN_EXISTING,
NULL, // no attributes
NULL // no template
);
if (hndlNP == INVALID_HANDLE_VALUE) {
printf("CreateFile error\n");
cout << "CreateFile error\n";
//return EXIT_FAILURE;
}
cout << "Pipe connection established\n";
QApplication app(argc, argv);
Window window(0, hndlNP);
window.resize(600, 600);
window.setWindowTitle("Pipe client");
window.show();
return app.exec();
}