Initial commit

vs4win/Chapter07/SharedLibrary/StringExtensions.cs

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+using System.Text.RegularExpressions;
+
+namespace Packt.Shared
+{
+  public static class StringExtensions
+  {
+    public static bool IsValidXmlTag(this string input)
+    {
+      return Regex.IsMatch(input,
+        @"^<([a-z]+)([^<]+)*(?:>(.*)<\/\1>|\s+\/>)$");
+    }
+
+    public static bool IsValidPassword(this string input)
+    {
+      // minimum of eight valid characters
+      return Regex.IsMatch(input, "^[a-zA-Z0-9_-]{8,}$");
+    }
+
+    public static bool IsValidHex(this string input)
+    {
+      // three or six valid hex number characters
+      return Regex.IsMatch(input,
+        "^#?([a-fA-F0-9]{3}|[a-fA-F0-9]{6})$");
+    }
+  }
+}