Computer Science 111 Fundamentals of Computer Programming I

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Computer Science 111Fundamentals of Computer
Programming I

• Additional Control Structures

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Control Structures - revisited

• Control structures have to do with the order in
  which the program statements are executed.
• Sequential flow is when we execute statements one
  after the other in the order they are written
  this is more or less the default.

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Control (cont.)

• Conditional flow is when a statement or group of
  statements is executed, or not, based on the
  current value of some condition. This is also
  called selection. We have seen this with if and
  if-these statements

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Control (cont.)

• Iteration is having the execution of a statement
  or group of statements to be repeated over and
  over based on some condition. We have used the
  while statement for this.

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The do-while statement

• Syntax do statement(s) while
  (condition)
• Style do statements while
  (condition)

• Note that the loop body is always executed once,
  and then the condition determines whether or not
  to repeat. This is a good choice when you want to
  allow the user to execute once and then decide
  whether or not to continue.

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do-while (cont.)

• Typical scenario do process
  goAgain reader.readChar(Continue? )
  while ((goAgain y) (goAgain
  Y))

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The for statement

• Syntax for (statement1 condition
  statement2) statement or
• for (statement1 condition statement2) stat
  ement statement

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The for statement

• for (statement1 condition statement2) statemen
  t

• Statement1 is executed once
• The condition is evaluated.
• If condition is true, the loop body and
  statement2 are executed.

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for loop example

• Add up the first 100 positive integers sum
  0 for (i1 ilt100 i) sum i
• Equivalent to sum 0 i1 while
  (ilt100) sum i i

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The switch statement

• This is another conditional statement somewhat
  like an extended if statement.
• Syntax switch (expression) case
  literal-1 group of statements break case
  literal-2 group of statements break
  case literal-n group of statements break
  default // Optional part group of
  statements break

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Switch Example
switch (score/10) case 10 case 9
writer.println("A") break case 8
writer.println("B") break case 7
writer.println("C") break case
6 writer.println(D") break
default writer.println(F")
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Could we hear more from the string section,
please?