.NET Core 2.0 has Path.GetRelativePath, else, use this.
/// <summary>/// Creates a relative path from one file or folder to another./// </summary>/// <param name="fromPath">Contains the directory that defines the start of the relative path.</param>/// <param name="toPath">Contains the path that defines the endpoint of the relative path.</param>/// <returns>The relative path from the start directory to the end path or <c>toPath</c> if the paths are not related.</returns>/// <exception cref="ArgumentNullException"></exception>/// <exception cref="UriFormatException"></exception>/// <exception cref="InvalidOperationException"></exception>public static String MakeRelativePath(String fromPath, String toPath){ if (String.IsNullOrEmpty(fromPath)) throw new ArgumentNullException("fromPath"); if (String.IsNullOrEmpty(toPath)) throw new ArgumentNullException("toPath"); Uri fromUri = new Uri(fromPath); Uri toUri = new Uri(toPath); if (fromUri.Scheme != toUri.Scheme) { return toPath; } // path can't be made relative. Uri relativeUri = fromUri.MakeRelativeUri(toUri); String relativePath = Uri.UnescapeDataString(relativeUri.ToString()); if (toUri.Scheme.Equals("file", StringComparison.InvariantCultureIgnoreCase)) { relativePath = relativePath.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar); } return relativePath;}