In the typical linear search pseudocode, what value is returned if the target is not found?

• A. 0
• B. -1
• C. len(array)
• D. None

Answer: (B)

When a linear search doesn’t find the target, it returns a signal value that isn’t a valid position in the array. Since valid indices range from 0 to length minus 1, using -1 as the return value works perfectly as that signal. It’s a clear, unmistakable indicator that the search failed, because -1 can never be a real index.

This makes the follow-up check simple: if the result is -1, the target isn’t present; otherwise, the result tells you where it is. Other options don’t fit as cleanly: returning 0 could be mistaken for a found target at the first position, returning the array length isn’t a valid index, and while some languages use None, -1 is the conventional sentinel in this pseudocode style.