程序代码汇总第10章

原书P177-P178 代码 using System; class chapter10 { static void Main() { string[] names = new string[99]; string name; string[] someNames = new string[]{"David","Jennifer", "Donnie", "Mayo", "Raymond", "Bernica", "Mike", "Clayton", "Beata", "Michael"}; int hashVal; for (int i = 0; i < 10; i++) { name = someNames[i]; hashVal = SimpleHash(name, names); names[hashVal] = name; } ShowDistrib(names); } static int SimpleHash(string s, string[] arr) { int tot = 0; char[] cname; cname = s.ToCharArray(); for (int i = 0; i <= cname.GetUpperBound(0); i++) tot += (int)cname[i]; return tot % arr.GetUpperBound(0); } static void ShowDistrib(string[] arr) { for (int i = 0; i <= arr.GetUpperBound(0); i++) if (arr[i] != null) Console.WriteLine(i + " " + arr[i]); } } 原书P179 代码 static int BetterHash(string s, string[] arr) { long tot = 0; char[] cname; cname = s.ToCharArray(); for (int i = 0; i <= cname.GetUpperBound(0); i++) tot += 37 * tot + (int)cname[i]; tot = tot % arr.GetUpperBound(0); if (tot < 0) tot += arr.GetUpperBound(0); return (int)tot; } 原书P180 代码 static bool InHash(string s, string[] arr) { int hval = BetterHash(s, arr); if (arr[hval] == s) return true; else return false; } 原书P181-P182 代码 public class BucketHash { private const int SIZE = 101; ArrayList[] data; public BucketHash() { data = new ArrayList[SIZE]; for (int i = 0; i <= SIZE - 1; i++) data[i] = new ArrayList(4); } public int Hash(string s) { long tot = 0; char[] charray; charray = s.ToCharArray(); for (int i = 0; i <= s.Length - 1; i++) tot += 37 * tot + (int)charray[i]; tot = tot % data.GetUpperBound(0); if (tot < 0) tot += data.GetUpperBound(0); return (int)tot; } public void Insert(string item) { int hash_value; hash_value = Hash(item); if (data[hash_value].Contains(item)) data[hash_value].Add(item); } public void Remove(string item) { int hash_value; hash_value = Hash(item); if (data[hash_value].Contains(item)) data[hash_value].Remove(item); } } 原书P184 代码 Hashtable symbols = new Hashtable(); Hashtable symbols = new Hashtable(50); Hashtable symbols = new Hashtable(25, 3.0F); 原书P185 代码1 Hashtable symbols = new Hashtable(25); symbols.Add("salary", 100000); symbols.Add("name", "David Durr"); symbols.Add("age", 43); symbols.Add("dept", "Information Technology"); 原书P185 代码2 symbols["sex"] = "Male"; symbols["age"] = 44; 原书P186 代码1 using System; using System.Collections; class chapter10 { static void Main() { Hashtable symbols = new Hashtable(25); symbols.Add("salary", 100000); symbols.Add("name", "David Durr"); symbols.Add("age", 45); symbols.Add("dept", "Information Technology"); symbols["sex"] = "Male"; Console.WriteLine("The keys are: "); foreach (Object key in symbols.Keys) Console.WriteLine(key); Console.WriteLine(); Console.WriteLine("The values are: "); foreach (Object value in symbols.Values) Console.WriteLine(value); } } 原书P186 代码2 Object value = symbols["name"]; Console.WriteLine("The variable name's value is: " + value.ToString()); 原书P186-P187 代码 using System; using System.Collections; class chapter10 { static void Main() { Hashtable symbols = new Hashtable(25); symbols.Add("salary", 100000); symbols.Add("name", "David Durr"); symbols.Add("age", 45); symbols.Add("dept", "Information Technology"); symbols["sex"] = "Male"; Console.WriteLine(); Console.WriteLine("Hash table dump - "); Console.WriteLine(); foreach (Object key in symbols.Keys) Console.WriteLine(key.ToString() + ": " + symbols[key].ToString()); } } 原书P188 代码1 int numElements; numElements = symbols.Count; 原书P188 代码2 symbols.Clear(); 原书P188 代码3 symbols.Remove("sex"); foreach (Object key in symbols.Keys) Console.WriteLine(key.ToString() + ": " + symbols[key].ToString()); 原书P188 代码4 string aKey; Console.Write("Enter a key to remove: "); aKey = Console.ReadLine(); if (symbols.ContainsKey(aKey)) symbols.Remove(aKey); 原书P189-P191 代码 using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Collections; using System.IO; namespace WindowsApplication3 { public partial class Form1 : Form { private Hashtable glossary = new Hashtable(); public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { BuildGlossary(glossary); DisplayWords(glossary); } private void BuildGlossary(Hashtable g) { StreamReader inFile; string line; string[] words; inFile = File.OpenText(@"c:\words.txt"); char[] delimiter = new char[] { ',' }; while (inFile.Peek() != -1) { line = inFile.ReadLine(); words = line.Split(delimiter); g.Add(words[0], words[1]); } inFile.Close(); } private void DisplayWords(Hashtable g) { Object[] words = new Object[100]; g.Keys.CopyTo(words, 0); for (int i = 0; i <= words.GetUpperBound(0); i++) if (!(words[i] == null)) lstWords.Items.Add((words[i])); } private void lstWords_SelectedIndexChanged(object sender, EventArgs e) { Object word; word = lstWords.SelectedItem; txtDefinition.Text = glossary[word].ToString(); } } }