WPF programming, a method of TextBox carriage return and line feed

The TextBox 's AcceptsReturn property is set to True ,
you can wrap after a carriage return in the text box.

Setting the TextWrapping property to Wrap will cause the entered text to wrap to a new line when it reaches the edge of the TextBox control, and the TextBox control will be automatically expanded if necessary
to make room for a new line.

Setting the AcceptsReturn property to true will cause a new line to be inserted when the Return key is pressed, and the TextBox will be automatically expanded again if necessary
to make room for the new line.