c# - Method to highlighting Text in TextBox is inconsistent -

c# - Method to highlighting Text in TextBox is inconsistent -

currently using this method highlight text within textbox, works sometimes.

this code has verify if there contained space in entered text. if there space in text user should warned, , text within textbox has highlighted:

if (textbox.text.contains(" ")) { messagebox.show("sorry, value entered must not contain spaces.", "please come in valid value", messageboxbutton.ok, messageboximage.error); //highlights wrong text textbox.selectionstart = 0; textbox.selectionlength = textbox.text.length; }

why isn't method working me time , can prepare it?

it might problem when selecting length of textbox has no focus in current moment.

can seek add together check focus?

if (textbox.text.contains(" ")) { messagebox.show("sorry, value entered must not contain spaces.", "please come in valid value", messageboxbutton.ok, messageboximage.error); if(!textbox.focused) { textbox.focus(); } //highlights wrong text textbox.selectionstart = 0; textbox.selectionlength = textbox.text.length; }

also instead of current solution can utilize textbox.selectall():

if (textbox.text.contains(" ")) { textbox.selectall(); messagebox.show("sorry, value entered must not contain spaces.", "please come in valid value", messageboxbutton.ok, messageboximage.error); }

c# wpf textbox