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void MainWindow::on_actionConfig_triggered()
{
    Config w;
    w.show();
}

//reqdata.cpp
#include "reqdata.h"
 
ReqData::ReqData()
{
 
}
 
QString ReqData::req(string md5)
{
    QNetworkAccessManager *request = new QNetworkAccessManager;
    QString req_str = "http://md5.darkbyte.ru/api.php?q=" + QString::fromStdString(md5);
 
    QObject::connect(request, SIGNAL(finished(QNetworkReply*)),SLOT(ReqFinished()));
    QNetworkReply *reply = request->get(QNetworkRequest(QUrl(req_str)));
 
    QByteArray bytes = reply->readAll();
 
    delete[] request;
    return (QString)bytes;
}
 
void ReqData::ReqFinished()
{
 
}

//reqdata.h
#ifndef REQDATA_H
#define REQDATA_H
 
#include<QCoreApplication>
#include<QCoreApplication>
#include<QNetworkAccessManager>
#include<QNetworkReply>
#include<QByteArray>
#include<QUrl>
#include<QNetworkRequest>
#include <QTextStream>
#include<QTextCodec>
#include<QObject>
 
#include<iostream>
#include<stdio.h>
#include<string>
#include<fstream>
 
#include"func.h"
using namespace std;
 
class ReqData
{
public:
    ReqData();
 
public:
    QString req(string md5);
 
public slots:
    void ReqFinished();
};
 
#endif // REQDATA_H

QObject::connect(request, SIGNAL(finished(QNetworkReply*)),SLOT(ReqFinished()),Qt::DirectConnection);

connect(request,SIGNAL(finished()),SLOT(ReqFinished()));