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Pulling Digits Out of String to Sum Them

Pulling Digits Out of String to Sum Them

Question:
How do I pull out every second digit from a string and sum them?

Answer:
This is a rather unusual question, but it’s not that hard to accomplish.

What must iterate through each character of the string and”grab” the digits whose position is a multiple of two (2). There are acouple of ways to do this, but I took what I felt was the easierroute. Since this is more or less a binary problem, setting a Boolean valuewith each iteration works nicely. Here’s the logic:

  1. For all “odd” positions, set Boolean value to False;
  2. For all “even” positions, set Boolean value to True;
  3. If the Boolean value is true, grab that character and add it to a temporary buffer.
  4. Iterate through the buffer, and convert each character to an Integer while adding the converted value to an integer variable.

Here’s the code that accomplishes the above:

function AddEvenOrOddChars(S : String; OddOrEven : Boolean) : Integer;var  I   : Integer;  evn : Boolean;  buf : String;begin  Result := 0;  {If OddOrEven was passed as True, then the all odd positions   will be grabbed and summed. If False, then all even positions   will be grabbed and summed.}  evn := EvenOdd;  {First grab the even position characters}  for I := 1 to Length(S) do begin    if evn then      buf := buf + S[I];    {Set boolean to its opposite regardless of its current value.     If it’s currently true, then we’ve just grabbed a character.     Setting it to False will make the program skip the next one.}    evn := NOT evn;  end;  {Now, iterate through the buffer variable to add up the individual   values}  for I := 1 to Length(buf) do    Result := Result + StrToInt(buf[I]);end;

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