. Net determines whether the string is numeric or XXX

using system. text. regularexpressions;

RegEx digitregex = new RegEx (@ "^ [0-9] \ D * [.]? \ D * $ ");
If (! Digitregex. ismatch (textbox1.text ))
{
textbox1.text = "";
MessageBox. show ("only numbers can be entered! "," Prompt ");
}< SPAN class = "apple-converted-space">

^ [0-9] \ D * [.]? \ D * $ is a floating-point value that can be matched.
^ [0-9] \ D * $ is an integer that only matches.
NO detected digits exist in both of the preceding two digits, change by yourself *