how to know that string contains number in c# code example

Example 1: if string contains number c#

"abc3def".Any(c => char.IsDigit(c));

// Or to make it shorter:
"abc3def".Any(char.IsDigit);

Example 2: c# how do you check if a string contains only digits

if (str.All(char.IsDigit)) {
  Console.WriteLine("This string only contains numbers");
}