How to search for number in string with method Contains and Linq in c#? -

i create calculator have buttons numbers , operators basic operation (+, -,...) , want filter buttons numbers detect when clicked number (between 0-9). put new eventhadler convert sender button.

i wondering nice , easy way filter buttons numbers (using linq) did try far is

if(btn.text == btn.text.contains(x => x >= '0' && x <= '9'))      messagebox.show("number " + btn.text + " pressed!"); 

how make upper code workable?

if want know is number or not this. no linq required

linq way check numbers between 0 , 9

if(yourstring.tochararray().where(c=> c < '0' || c > '9').any())   return false; else  return true; 

to check contains valid number

double num; if (double.tryparse(btn.text, out num)) {     // it's number! } 

or check less 10 without linq

static bool islessthanten(string str) {     foreach (char c in str)     {         if (c < '0' || c > '9')             return false;     }      return true; }