Using lambda function in a foreach over controls [duplicate]

问题

This question already has answers here:

Foreach Control in form, how can I do something to all the TextBoxes in my Form? (14 answers)

Closed 3 years ago.

I would like to translate this:

foreach(Control c in Controls)
{
    if(c is TextBox)
    {
        // ...
    }
}

Into:

foreach(Control c => (c is TextBox) in Controls)
{
    // ...
}

How can it be done using the lambda function specifically?

回答1:

Reference Linq:

using System.Linq;

And use this:

foreach (var control in Controls.Cast<Control>().Where(c => c is TextBox))
{
    // ...
}

回答2:

Use OfType:

foreach (TextBox c in Controls.OfType<TextBox>())
{

}

It filters the elements of an IEnumerable based on a specified type.

Also don't forget to add LINQ to your using directives first:

using System.Linq;

回答3:

You are looking for something like this:

foreach(TextBox ctrlTxtBox in Controls.OfType<TextBox>())
{
   // Got it code here
}

OfType Filters the elements of an IEnumerable based on a specified type.

来源：https://stackoverflow.com/questions/47179959/using-lambda-function-in-a-foreach-over-controls