I am working on a Circularly-Doubly-Linked List with a sentinel in the C language with the 99 standard. The headers I am allowed to use for class are stdio.h, stdlib.h, and assert.h only.
The sentinel is a struct and the structs have a value data member which is a double value. I was wondering if there is a substitute for NULL with doubles? It appears NULL can be used for integer data types but not doubles. I tried using Nan and NAN but the compiler is not accepting these. I considered using an arbitrary number, but wanted to know if there was a specific stand-in for NULL in this particular situation?