Sentinel value

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In computer programming, a sentinel value (also referred to as a flag value, rogue value, or signal value) is a special value that is used to terminate a loop that processes structured (especially sequential) data. The value should be selected in such a way that it will not be confused with legal data values.

Below are some examples of common sentinel values and their uses:

• Null character for indicating the end of a null-terminated string.
• Null pointer for indicating the end of a linked list.
• The empty list, (), in Lisp and its variants.

Sentinel values are often used when searching for something.^[1]

[edit] See also

• Sentinel node

[edit] Notes

1. ^ McConnell, Steve. "Code Complete" Edition 2 Pg. 621 ISBN - 0-7356-1967-0