Steven Pemberton, CWI, Amsterdam.
This is a program that determines many properties of the C compiler and machine that it is run on, such as minimum and maximum [un]signed char/int/long, many properties of float/ [long] double, and so on.
As an option it produces the ANSI C float.h and limits.h files.
As a further option, it even checks that the compiler reads the header files correctly.
It is a good test-case for compilers, since it exercises them with many limiting values, such as the minimum and maximum floating-point numbers.
The C source contains a long preamble comment that explains how to compile and run it.