Qt signals and slots with parameters

In C++ custom signals and slots, they sometimes take parameters.

//假定信号函数如下
void singleimagedropped(Url url);

//假定槽函数如下
void loadsingleimage(Url url)

There are two ways to connect to this

//Qt4
connect(signal sender, SIGNAL(singleimagedropped), signal receiver, SLOT(loadsingleimage));
//Qt5
void (*singleimagedropped)(QUrl) = &singleImageDropped;
void (loadsingledropped)(QUrl) = loadSingleDropped;
connect( signal sender, singleimagedropped, signal receiver,
loadsingledropped);