[Solved]what does this syntax mean in c++?

[whitesong]

I want to know what this syntax says:

@(void) new ClassName();@

the syntax above is used in this snip code for populate a widget.

@ void populateTree(QTreeWidget *treeWidget)
{
QStringList labels;
labels << QObject::tr("Terms") << QObject::tr("Pages");

    treeWidget->setHeaderLabels(labels);
    treeWidget->header()->setResizeMode(QHeaderView::Stretch);
    treeWidget->setWindowTitle(QObject::tr("XML Stream Writer"));
    treeWidget->show();

    (void) new QTreeWidgetItem(treeWidget,
            QStringList() << "sidebearings" << "10, 34-35, 307-308");
    QTreeWidgetItem *subterm = new QTreeWidgetItem(treeWidget,
            QStringList() << "subtraction");
    (void) new QTreeWidgetItem(subterm,
            QStringList() << "of pictures" << "115, 244");
    (void) new QTreeWidgetItem(subterm,
            QStringList() << "of vectors" << "9");
}@

[coyotte508]

The (void) doesn't do anything, it just removes some warnings for some IDEs to tell it's normal the result of the "new" isn't stored in any variable.

[whitesong]

thanks. so in some IDEs "(void)" will be needed

[utcenter]

It is not needed in any of the popular IDEs and compilers.

[JKSH]

[quote author="whitesong" date="1367141103"]thanks. so in some IDEs "(void)" will be needed[/quote]It's not really needed, but it's nice to get rid of compiler warnings.

In this code below, your compiler might warn you that x and y are unused. :
@
void myFunction(int x)
{
int y = 1;
return; // Produces a warning that x and y are unused
}
@

But, calling (void) tells the compiler to "do nothing" with the variables, so it won't complain:

@
void myFunction(int x)
{
int y = 1;

// Prevents warnings
(void) x;
(void) y;

return;

}
@

Qt has its own macro to do this, instead of (void). The code below has exactly the same effect as the code above:
@
void myFunction(int x)
{
int y = 1;

// Prevents warnings
Q_UNUSED(x);
Q_UNUSED(y);

return;

}
@

[whitesong]

Oh thanks again everyone.
I really understand what is going on with your explanation .

[whitesong]

Oh thanks again everyone.
I really understand what is going on with your explanation.