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  1. using System;
  2. using System.Text;
  3. using System.Globalization;
  4.  
  5. public class Test
  6. {
  7. 	public static void Main()
  8. 	{
  9. 		var myString = @"This is a string before an emoji:🔹This is after the emoji.";
  10. 		var teMyString = new StringInfo(myString);
  11. 		Console.WriteLine("TextElements Substring:");
  12. 		Console.WriteLine($"0-33:{teMyString.SubstringByTextElements(0, 33)}");
  13. 		Console.WriteLine($"0-34:{teMyString.SubstringByTextElements(0, 34)}");
  14. 		Console.WriteLine($"0-35:{teMyString.SubstringByTextElements(0, 35)}");
  15. 		Console.WriteLine("Custom Xanatos's substring:");
  16. 		Console.WriteLine($"0-33:{StringEx.UnicodeSafeSubstring(myString, 0, 33)}");
  17. 		Console.WriteLine($"0-34:{StringEx.UnicodeSafeSubstring(myString, 0, 34)}");
  18. 		Console.WriteLine($"0-35:{StringEx.UnicodeSafeSubstring(myString, 0, 35)}");
  19.  
  20. 	}
  21. }
  22. public static class StringEx
  23. {
  24.     public static string UnicodeSafeSubstring(string str, int startIndex, int length)
  25.     {
  26.         if (str == null)
  27.         {
  28.             throw new ArgumentNullException("str");
  29.         }
  30.  
  31.         if (startIndex < 0 || startIndex > str.Length)
  32.         {
  33.             throw new ArgumentOutOfRangeException("startIndex");
  34.         }
  35.  
  36.         if (length < 0)
  37.         {
  38.             throw new ArgumentOutOfRangeException("length");
  39.         }
  40.  
  41.         if (startIndex + length > str.Length)
  42.         {
  43.             throw new ArgumentOutOfRangeException("length");
  44.         }
  45.  
  46.         if (length == 0)
  47.         {
  48.             return string.Empty;
  49.         }
  50.  
  51.         var sb = new StringBuilder(length);
  52.  
  53.         int end = startIndex + length;
  54.  
  55.         var enumerator = StringInfo.GetTextElementEnumerator(str, startIndex);
  56.  
  57.         while (enumerator.MoveNext())
  58.         {
  59.             string grapheme = enumerator.GetTextElement();
  60.             startIndex += grapheme.Length;
  61.  
  62.             if (startIndex > length)
  63.             {
  64.                 break;
  65.             }
  66.  
  67.             // Skip initial Low Surrogates/Combining Marks
  68.             if (sb.Length == 0)
  69.             {
  70.                 if (char.IsLowSurrogate(grapheme[0]))
  71.                 {
  72.                     continue;
  73.                 }
  74.  
  75.                 UnicodeCategory cat = char.GetUnicodeCategory(grapheme, 0);
  76.  
  77.                 if (cat == UnicodeCategory.NonSpacingMark || cat == UnicodeCategory.SpacingCombiningMark || cat == UnicodeCategory.EnclosingMark)
  78.                 {
  79.                     continue;
  80.                 }
  81.             }
  82.  
  83.             sb.Append(grapheme);
  84.  
  85.             if (startIndex == length)
  86.             {
  87.                 break;
  88.             }
  89.         }
  90.  
  91.         return sb.ToString();
  92.     }
  93. }
Success #stdin #stdout 0s 131648KB
comments (?)
stdin
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Standard input is empty
stdout
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TextElements Substring:
0-33:This is a string before an emoji:
0-34:This is a string before an emoji:🔹
0-35:This is a string before an emoji:🔹T
Custom Xanatos's substring:
0-33:This is a string before an emoji:
0-34:This is a string before an emoji:
0-35:This is a string before an emoji:🔹
https://ideone.com/OcSafo
language:
C# (gmcs 5.20.1)
created:
8 years ago
visibility:
secret

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