Set all Labels Font before opening the Form

问题

Before opening the form I used following code to check if its label then change the font

foreach (Label ctl in frm.Controls)
{
    ctl.Font = usefontgrid;
}

But on first line return error because it check other control types such as textbox or button,etc.

How can I check if the object is only label then go to for each?

回答1:

Try this;

foreach (Control c in this.Controls)
{
    if (c is Label)
        c.Font = usefontgrid;
}

Or

foreach (var c in this.Controls.OfType<Label>())
{
    c.Font = usefontgrid;
}

回答2:

Its not clear where you place this code (should be after initialize component) but try

foreach (Label ctl in frm.Controls.OfType<Label>())
{
    ctl.Font = usefontgrid;
}

There is also the following Linq to do the same thing

foreach (Label ctl in frm.Controls.Where(x => x is Label))

回答3:

try this.

 foreach (Control ctl in frm.Controls)
    {
    if(ctl.GetType()==typeof(Label)){
        ctl.Font = usefontgrid;
    }
    }

1. frm.controls will give all controls
2. You need to check whether the control is a type of Label.

来源：https://stackoverflow.com/questions/18481029/set-all-labels-font-before-opening-the-form