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c++pseudocode

what does returning -1 mean in a pseudocode

I have the following pseudocode which a sequential search pseudocode and I am trying to understand what return -1 mean. why would we return -1 could someone please explain. 

A[n] <-- K
i <-- 0
while A[i] != K do
     i = i + 1
if(i<n)
     return i;
else
     return -1;       //What is this mean ?
Solution

  • Returning -1 is a way of conveying the fact that the code reached the end without returning in the middle. Returning -1 in this case means that the element K does not exist in the array.

    Note that returning 0 is not used for this purpose as it could mean the element is present at the 0th index. If your function was something which could return -1 at some point in the middle, some other return value to indicate failure would have been chosen.