文字列内の単語の出現数を数える C# プログラム

string str = "Hello World! Hello!";

while ((a = str1.IndexOf(pattern, a)) != -1) { a += pattern.Length; count++; }

using System; class Program { static void Main() { string str = "Hello World! Hello!"; Console.WriteLine("Occurrence:"+Check.CheckOccurrences(str, "Hello")); } } public static class Check { public static int CheckOccurrences(string str1, string pattern) { int count = 0; int a = 0; while ((a = str1.IndexOf(pattern, a)) != -1) { a += pattern.Length; count++; } return count; } }

Occurrence:2