練習題 (12)： Extract uppercase words from a file, extract unique words.
本題可以利用 Regex 類別擷取檔案中所有的單字，並將單字放進 .NET 的泛型 Hash Table：Dictionary 類別中計算單字與其出現次數。
測試檔案內容：
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In this file, THERE ARE some UPPERCASE words.
And, There ARE some redundant WORDS IN the content:
foo bar foo CSHARP Dictionary CSHARP Firefox Opera IE
JUST FOR FUN.
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程式碼：
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Text.RegularExpressions;
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namespace DictionaryTest
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{
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internal class Program
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{
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private static void Main( string [ ] args)
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{
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StreamReader sr = new StreamReader ( "in.txt" );
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Dictionary<string, int> d = new Dictionary<string, int> ( );
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while (sr.Peek ( ) != -1 )
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{
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string s = sr.ReadToEnd ( );
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Regex r = new Regex ( @"(\w+)", RegexOptions. IgnoreCase );
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Match m = r.Match (s);
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while (m.Success )
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{
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Group g = m.Groups [ 1 ];
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if (!d.ContainsKey (g.ToString ( ) ) )
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{
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d.Add (g.ToString ( ), 1 );
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}
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else
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{
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d[g.ToString ( ) ] += 1;
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}
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m = m.NextMatch ( );
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}
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}
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Console.WriteLine ( "Uppercase words:" );
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Dictionary<string, int>.KeyCollection kc = d.Keys;
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foreach ( string s in kc)
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{
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if (Regex.IsMatch (s, @"^[A-Z]+$" ) )
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{
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Console.WriteLine (s);
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}
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}
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Console.WriteLine ( "Unique words:" );
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foreach (KeyValuePair<string, int> kvp in d)
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{
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if (kvp.Value == 1 )
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{
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Console.WriteLine (kvp.Key );
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}
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}
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sr.Dispose ( );
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}
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}
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}
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