Break and continue statements Array Examples

1
Lecture 10

• Break and continue statements Array Examples
• Reference Section 4.9, 4.12, 6.4

2
break and continue Statements

• break and continue statements are used to alter
  the flow of control.
• break
• Causes immediate exit from a while, for, dowhile
  or switch statement
• Program execution continues with the first
  statement after the structure
• Common uses of the break statement
• Escape early from a loop
• Skip the remainder of a switch statement

3
(No Transcript)
4
break and continue Statements

• continue
• Skips the remaining statements in the body of a
  while, for or dowhile statement
• Proceeds with the next iteration of the loop
• while and dowhile
• Loop-continuation test is evaluated immediately
  after the continue statement is executed
• for
• Increment expression is executed, then the
  loop-continuation test is evaluated

5
(No Transcript)
6
Summary of Structured Programming

• Structured programming promotes simplicity
• Only three forms of control are needed
• Sequence
• Selection
• if
• if else
• switch
• Repetition
• while
• do while
• for

7
Summary of Structured Programming
8
Summary of Structured Programming
9
Rules for Forming Structured Programs

• Begin with the simplest flowchart
• Any rectangle (action) can be replaced by two
  rectangles (actions) in sequence
• Stacking rule
• Any rectangle (action) can be replaced by any
  control statement (sequence, if, ifelse, switch,
  while, do .. While, or for)
• Nesting rule
• Rules 2 and 3 may be applied as often as you like
  and in any order

10
Rules for Forming Structured Programs
Simplest flowchart
11
Rules for Forming Structured Programs
Repeatedly applying rule 2 (stacking rule) to the
simplest flowchart
12
Rules for Forming Structured Programs
Applying rule 3 (nesting rule) to the simplest
flowchart.
13
Array Examples

• Initializers
• int n 5 1, 2, 3, 4, 5
• If not enough initializers, rightmost elements
  become 0
• int n 5 0
• All elements are 0
• If too many initializers, a syntax error occurs
• C arrays have no bounds checking
• If size omitted, initializers determine it
• int n 1, 2, 3, 4, 5
• 5 initializers, therefore 5 element array

14
Outline

• fig06_03.c

15
Outline

• fig06_04.c

16
Common Programming Errors

• Forgetting to initialize the elements of an array
  whose elements should be initialized.
• Providing more initializers in an
  arrayinitializer list than there are elementsin
  the array is a syntax error.

17
Outline

• fig06_05.c

Element Value 0 2 1
4 2 6 3
8 4 10 5 12
6 14 7 16 8
18 9 20
18
Outline

• fig06_06.c

19
Outline

• fig06_07.c
• (1 of 2 )

20
Outline

• fig06_07.c
• (2 of 2 )

21
Error-Prevention Tips

• When looping through an array, the array
  subscript should never go below 0 and should
  always be less than the total number of elements
  in the array (size 1). Make sure the
  loop-terminating condition prevents accessing
  elements outside this range.
• Programs should validate the correctness of all
  input values to prevent erroneous information
  from affecting a programs calculations.

22
Outline

• fig06_08.c
• (1 of 2 )

23
Outline

• fig06_08.c
• (2 of 2 )

24
Appendix C Keywords

• auto break case char
• const continue default do
• double else enum extern
• float for goto if
• int long register return
• short signed sizeof static
• struct switch typedef union
• unsigned void volatile while