分解:
string s = "abcdeabcdeabcde";
            string[] sArray = s.Split('c');
            foreach (string i in sArray)
            {
                textBox1.Text += i.ToString() + "@";
                }
截取
string s = "abcdeabcdeabcde";
            s = s.Substring(0, 5);
            textBox1.Text = s;
 
替换:
           string s = "abcdeabcdeabcde";
            s = s.Replace("ea", "$$");
            textBox1.Text = s;
量长度
     string s = "abcdeabcdeabcde";
        int slen = s.Length;
            textBox1.Text = slen.ToString();
插入
string s = "abcdeabcdeabcde";
             s= s.Insert(5, "@@");
            textBox1.Text = s;
比较
string s = "abcdeabcdeabcde";
            int ss = s.CompareTo("a");
            textBox1.Text = ss.ToString();
补齐
string s = "abcdeabcdeabcde";
            s = s.PadLeft(20,'0');//  必须用单引号
            textBox1.Text = s;