C＃如何在arraylist中打印字符串的字符

Question

該程序將打印所有可能的字符串輸入，例如，如果輸入為abc'，則輸出應為組合，這是可行的，但是當我創建arraylist時，它將打印出數字而不是字符串組合，代碼：

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);
}

arraylist的輸出是數字而不是字符串char，請幫助！

Answer 1

只需更改這三行

從：

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

至：

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

Answer 2

備選：更改一行：

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

char不能像string那樣string 。 +數字解釋。