System.Environment.Environment.ExpandEnvironmentVariables C# (CSharp) Méthode

		public static string ExpandEnvironmentVariables (string name)
		{
			if (name == null)
				throw new ArgumentNullException ("name");

			int off1 = name.IndexOf ('%');
			if (off1 == -1)
				return name;

			int len = name.Length;
			int off2 = 0;
			if (off1 == len - 1 || (off2 = name.IndexOf ('%', off1 + 1)) == -1)
				return name;

			StringBuilder result = new StringBuilder ();
			result.Append (name, 0, off1);
			Hashtable tbl = null;
			do {
				string var = name.Substring (off1 + 1, off2 - off1 - 1);
				string value = GetEnvironmentVariable (var);
				if (value == null && Environment.IsRunningOnWindows) {
					// On windows, env. vars. are case insensitive
					if (tbl == null)
						tbl = GetEnvironmentVariablesNoCase ();

					value = tbl [var] as string;
				}
				
				// If value not found, add %FOO to stream,
				//  and use the closing % for the next iteration.
				// If value found, expand it in place of %FOO%
				if (value == null) {
					result.Append ('%');
					result.Append (var);
					off2--;
				} else {
					result.Append (value);
				}
				int oldOff2 = off2;
				off1 = name.IndexOf ('%', off2 + 1);
				// If no % found for off1, don't look for one for off2
				off2 = (off1 == -1 || off2 > len-1)? -1 :name.IndexOf ('%', off1 + 1);
				// textLen is the length of text between the closing % of current iteration
				//  and the starting % of the next iteration if any. This text is added to output
				int textLen;
				// If no new % found, use all the remaining text
				if (off1 == -1 || off2 == -1)
					textLen = len - oldOff2 - 1;
				// If value found in current iteration, use text after current closing % and next %
				else if(value != null)
					textLen = off1 - oldOff2 - 1;
				// If value not found in current iteration, but a % was found for next iteration,
				//  use text from current closing % to the next %.
				else
					textLen = off1 - oldOff2;
				if(off1 >= oldOff2 || off1 == -1)
					result.Append (name, oldOff2+1, textLen);
			} while (off2 > -1 && off2 < len);
				
			return result.ToString ();

		}