Difference between := and ← in pseudocode

Problem Detail: 

This is a snippet from some pseudocode for a sorting algorithm. In it, the symbol ← is used to denote assignment, for example for the variable done. However, in the while loop the statement done:= false is written. I would assume it is also an assignment statement but I suspect it means somethings else, or perhaps extra, since if not, the ← would have simple be used again.

Algorithm MyAlgorithm(A, n)      Input: Array of integer containing n elements      Output: Possibly modified Array A  done ← true  j ← 0 while j ≤ n - 2 do      if A[j] > A[j + 1] then         swap(A[j], A[j + 1])         done:= false      j ← j + 1 

Asked By : CodyBugstein

Answered By : Eric

The use of := in this context appears to be a slip-up from whomever it is who wrote that pseudocode. The initial impression given is that they have different meanings (I thought at first that := was perhaps "redefine", and that ← was "declare and define"). However, with the use of j ← j + 1 on the line following it, it seems clear that the := was a mistake.

In general, := and = are the most common assignment operators, seemingly in both pseudocode and real code. You may be interested in looking at notations of the assignment operator in various programming languages, which include :=, =, <-, ←, and many others.

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Question Source : http://cs.stackexchange.com/questions/8995