C＃如何在arraylist中打印字符串的字符

Question

This program prints all possibilities of a string input, for example, if input is abc', the output should be the combinations, this works but when im creating the arraylist it's printing out numbers instead of the string combinations, code:

string input = Console.ReadLine();

int sl = input.Length;
ArrayList arr = new ArrayList();

for (int three = 0; three < sl; three++) {
    for (int two = 0; two < sl; two++) {
        for (int one = 0; one < sl; one++) {
            char onef = input[one];
            char twof = input[two];
            char threef = input[three];


            arr.Add(threef + twof + onef);

            Console.Write(threef);
            Console.Write(twof);
            Console.WriteLine(onef);
        }
    }
}

Console.WriteLine("The elements of the ArrayList are:");
foreach(object obj in arr) {
    Console.WriteLine(obj);
}

the output of the arraylist is numbers and not the string chars, help!

Answer 1

Just change these three lines

From:

 char onef = input[one];
 char twof = input[two];
 char threef = input[three];

To:

  string onef = input[one].ToString();
  string twof = input[two].ToString();
  string threef = input[three].ToString();

Answer 2

Alternate: change one line:

arr.Add(string.Format("{0}{1}{2}", a, b, c));

char cannot be concatenated like string . The + is interpreted numerically.