Mithat Konar
2013-02-28

• Input validation
• Sentinel/flag control
• Counter control
• Iterators

• “Block moving to next section until user has entered valid data.”
• Pseudo code:

  Get input value from user
  While input value is not valid
      Get input value from user

• Sentinel:
  • Value(s) that indicate(s) a special condition; “special value”
• Flag:
  • Sometimes used as a synonym for sentinel
  • Sometimes means a sentinel that is a Boolean value

• “Repeat as long as a sentinel condition is not matched.”
• Pseudo code:

  Get input value
  While input value is not SENTINEL value
      Do something
      Get input value

• Input validation might be considered a special case of sentinel controlled repetition.

• Repeating menus can be implemented with sentinel control.
• Pseudo code:

  Show menu
  Get menu choice from user
  While input value is not QUIT value
      <Process the menu choice>
      Show menu
      Get menu choice from user

• “Repeat something a known number of times.”
• Uses a counter variable.
• Pseudo code:

  Set counter's initial value
  While counter has not yet exceeded the STOP_VALUE
      Do something
      Increment counter

• Do something to every item in a collection.
• Pseudo code:

  For each item in collection
      Do something with or to the item