C# .NET equivalent to PHP time()

(int)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds

It's not clear why you need an equivalent for PHP time(), but you can do:

var secondsSinceUnixEpoch = DateTime.UtcNow
                                    .Subtract(new DateTime(1970, 1, 1))
                                    .TotalSeconds;

// If needed.
var roundedSeconds = (int) secondsSinceUnixEpoch;