How to identify if a string contains more than one instance of a specific character?

Question

I want to check if a string contains more than one character in the string? If i have a string 12121.23.2 so i want to check if it contains more than one . in the string.

Answer 1

You can compare IndexOf to LastIndexOf to check if there is more than one specific character in a string without explicit counting:

var s = "12121.23.2";
var ch = '.';
if (s.IndexOf(ch) != s.LastIndexOf(ch)) {
    ...
}

Answer 2

You can easily count the number of occurences of a character with LINQ:

string foo = "12121.23.2";
foo.Count(c => c == '.');