Mithat Konar
2019-02-11

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

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

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

• Sentinel:
  • Value(s) that indicate(s) a special condition — a “special value”

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

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

• Input validation might be considered a special case of sentinel controlled repetition.
• Flag:
  • Sometimes used as a synonym for sentinel
  • Sometimes means a sentinel that is a Boolean value

• “Prevent moving to next section until user has entered valid data.”
• Pseudocode:

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

• Repeating menus can be implemented with sentinel control.
• Pseudocode:

  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

• Do something to every item in a collection.
• Pseudocode:

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