Is this a right statement?

From: Sam Kong (
Date: 02/11/05

Date: 10 Feb 2005 15:34:32 -0800


I read an article and read the following sentence.
I am not sure what that means.

Then there was Simula, which the designers thought of as an extension
of Algol. It was basically a preprocessor to Algol the way C++ was a
preprocessor for C.

Is C++ a preprocessor for C?
What does that mean?
Is it right?