Pseudocode Conventions

Notes

• INSERTION-SORT(A)
  
   for j = 2 to to A.length
      key = A[j]
      i = j-1
      while i > 0 and A[i] > key
          A[i+1] = A[i]
          i = i - 1
      A[i+1] = key
  

• I will mostly follow the book's pseudocode notation
• Why pseudocode ?

  •  void InsertionSort(vector & A) {
        for(int j = 1; j < A.size(); ++j) {
           int key = A[j];
           int i = j-1;
           while (i >= 0 and A[i] > key) {
               A[i+1] = A[i];
               --i;
           }
           A[i+1] = key;
        }
    }

  • Is there a major difference?
  • You might want to look at the full code.
• Pseudocode conventions (from the book)
  • Use program control structures
    • if, if/else, if/elseif/elseif/else
    • case
    • while, for, repeat-until
  • No code blocks, indentation like python
  • // for comments
  • a = b = c is permitted
  • variables are local, no globals
  • Parameters are pass by value
    • Objects are passed by pointer.
    • But arrays are passed by pointer.
  • [] for array access, arrays start at 1
    • Already noted
    • I am sure I will goof this up.
  • Objects have attributes (A.length)
  • Return can return 0 or more objects
  • Short circuit evaluation
    • line 4 above will not cause an error.
  • error is like a c++ exception