/// <summary>Determines whether a path includes a file name extension.</summary>
/// <returns>true if the characters that follow the last directory separator (\\ or /) or volume separator (:) in the path include a period (.) followed by one or more characters; otherwise, false.</returns>
/// <param name="path">The path to search for an extension. </param>
/// <exception cref="T:System.ArgumentException">
/// <paramref name="path" /> contains one or more of the invalid characters defined in <see cref="M:System.IO.Path.GetInvalidPathChars" />. </exception>
/// <filterpriority>1</filterpriority>
public static bool HasExtension(string path)
{
if (path == null || path.Trim().Length == 0)
{
return(false);
}
if (path.IndexOfAny(Path.InvalidPathChars) != -1)
{
throw new ArgumentException("Illegal characters in path.");
}
int num = Path.findExtension(path);
return(0 <= num && num < path.Length - 1);
}
/// <summary>Returns the extension of the specified path string.</summary>
/// <returns>A <see cref="T:System.String" /> containing the extension of the specified path (including the "."), null, or <see cref="F:System.String.Empty" />. If <paramref name="path" /> is null, GetExtension returns null. If <paramref name="path" /> does not have extension information, GetExtension returns Empty.</returns>
/// <param name="path">The path string from which to get the extension. </param>
/// <exception cref="T:System.ArgumentException">
/// <paramref name="path" /> contains one or more of the invalid characters defined in <see cref="M:System.IO.Path.GetInvalidPathChars" />. </exception>
/// <filterpriority>1</filterpriority>
public static string GetExtension(string path)
{
if (path == null)
{
return(null);
}
if (path.IndexOfAny(Path.InvalidPathChars) != -1)
{
throw new ArgumentException("Illegal characters in path.");
}
int num = Path.findExtension(path);
if (num > -1 && num < path.Length - 1)
{
return(path.Substring(num));
}
return(string.Empty);
}
/// <summary>Changes the extension of a path string.</summary>
/// <returns>A string containing the modified path information.On Windows-based desktop platforms, if <paramref name="path" /> is null or an empty string (""), the path information is returned unmodified. If <paramref name="extension" /> is null, the returned string contains the specified path with its extension removed. If <paramref name="path" /> has no extension, and <paramref name="extension" /> is not null, the returned path string contains <paramref name="extension" /> appended to the end of <paramref name="path" />.</returns>
/// <param name="path">The path information to modify. The path cannot contain any of the characters defined in <see cref="M:System.IO.Path.GetInvalidPathChars" />. </param>
/// <param name="extension">The new extension (with or without a leading period). Specify null to remove an existing extension from <paramref name="path" />. </param>
/// <exception cref="T:System.ArgumentException">
/// <paramref name="path" /> contains one or more of the invalid characters defined in <see cref="M:System.IO.Path.GetInvalidPathChars" />.</exception>
/// <filterpriority>1</filterpriority>
public static string ChangeExtension(string path, string extension)
{
if (path == null)
{
return(null);
}
if (path.IndexOfAny(Path.InvalidPathChars) != -1)
{
throw new ArgumentException("Illegal characters in path.");
}
int num = Path.findExtension(path);
if (extension == null)
{
return((num >= 0) ? path.Substring(0, num) : path);
}
if (extension.Length == 0)
{
return((num >= 0) ? path.Substring(0, num + 1) : (path + '.'));
}
if (path.Length != 0)
{
if (extension.Length > 0 && extension[0] != '.')
{
extension = "." + extension;
}
}
else
{
extension = string.Empty;
}
if (num < 0)
{
return(path + extension);
}
if (num > 0)
{
string str = path.Substring(0, num);
return(str + extension);
}
return(extension);
}
