nullsentinel
Nullsentinel refers to a sentinel value used to mark the end of a sequence or the absence of a meaningful value within a data structure. It is a general concept found across programming languages, where a specific value serves as a terminator or placeholder to simplify iteration and boundary checks. The exact form of a nullsentinel depends on the data type and language: a null pointer, a zero, a nil, a special token, or a reserved object may play this role.
Common examples include the null terminator in C-style strings, where the character '\0' marks the end of
Design considerations: choose a value that cannot occur in valid data, or use a sentinel node—a dedicated
Related concepts include sentinel nodes, which are actual nodes representing boundaries; end markers and length fields