Passing parameters between methods

See more:

C#

I have a list of different characters written in a richtextbox.Now i want to pull one by one from the list using a loop and want to examine whether it is number or special character or word etc.

var items = listView1.Items;
for (int i = 0; i < list.Count; i++)
{
    matchNumber(list[i].ToString(),""); //this loop isn't complete

}

public void matchNumber(string number,string message)
{
    if (number == "0" || number == "1" || number == "2" || number == "3" || number == "4" || number == "5" || number == "6" || number == "7" || number == "8" || number == "9")
        message = "number";
}

public void matchSpecialCharacter(string specialCharacter, string message)
{
    if (specialCharacter == "," || specialCharacter == ";" || specialCharacter == "{" || specialCharacter == "}" || specialCharacter == "[" || specialCharacter == "]" || specialCharacter == "+" || specialCharacter == "-" || specialCharacter == "*" || specialCharacter == "/" || specialCharacter == "%")
        message = "special character";
}

matchNumber and matchSpecialCharacter are methods to filter each list[i] item.So i need to pass each list[i] to those methods as a parameter and return message as another parameter from those methods to print in loop.So how can i configure that loop to print it successfully for each list[i],whether it is number or other character.