how to see if string only numbers c# code example

Example 1: c# how to check string is number

string s1 = "123";
string s2 = "abc";

bool isNumber = int.TryParse(s1, out int n); // returns true
isNumber = int.TryParse(s2, out int n); // returns false

Example 2: c# check if string is only letters and numbers

if (textVar.All(c => Char.IsLetterOrDigit(c))) {
    // String contains only letters & numbers
}