Structured%20Programming

1
Programming

• Structured Programming

2
Structured Programming

• Structured programing is the set of design and
  implementation processes that yield
  well-structured programs.

3
Structured Programming

• A disciplined approach to programming
• Top-down design
• Step-wise refinement using a restricted set of
  program structures
• The set of program structures used in
  structured programming is
• Sequence
• Choice
• Loop

4
Top-Down Design

• A program is divided into a main module and its
  related modules. Each module is in turn divided
  into submodules until the resulting modules are
  understood without further division.

5
Stepwise Refinement

• Any action can be
• another
• Sequence
• Choice
• Loop

initialization
condition_x
false
condition
false
true
true
action_x
action_y
update
6
A Sequence

• It is natural to write a program as a
  sequence of program structures such as sequences,
  choices and loops.

Action 1
Action 2
Action N
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A Choice Statement

• Syntax
• if(condition)
• action
• if the condition is true then execute the action.
• action is either a single statement or a group of
  statements within braces.

condition
false
true
action
8
Another Choice Statement

• Syntax
• if (condition)
• Action_A else Action_B
• if the condition is true
• execute Action_A
• else
• execute Action_B.

condition
true
false
Action_A
Action_B
9
A Loop Statement

• Syntax
• while (condition)
• action
• How it works
• if condition is true then execute action
• repeat this process until condition evaluates to
  false
• action is either a single statement or a group of
  statements within braces.

condition
false
true
action
10
Another Loop Statement

• Syntax
• for (initialization condition update)
• action
• How it works
• execute initialization
• statement
• while condition is true
• execute action
• execute update

initialization
condition
false
true
action
update
11
Yet Another Loop Statement

• Syntax
• do action
• while (condition)
• How it works
• execute action
• if condition is true then execute action again
• repeat this process until condition evaluates to
  false.
• action is either a single statement or a group of
  statements within braces.

action
condition
true
false
12
Diamond Pattern

• Print out the following diamond pattern

13
Diamond Pattern

• Sub-problem
• print out the upper half
• print out the lower half
• Print out upper half
• row 1 print 4 spaces, 1 star
• row 2 print 3 spaces, 3 stars
  
• row 3 print 2 spaces, 5 stars
  
• row 4 print 1 space, 7 stars
  
• row 5 print 0 spaces, 9 stars
  
• Print out lower half
• row 4 print 1 space, 7 stars
  
• row 3 print 2 spaces, 5 stars
  
• row 2 print 3 spaces, 3 stars
  
• row 1 print 4 spaces, 1 star
  

14
Diamond Pattern

• Algorithm for upper half
• row 1 print (5-row)spaces, (2row - 1) stars
  
• row 2 print (5-row)spaces, (2row - 1) stars
  
• row 3 print (5-row)spaces, (2row - 1) stars
  
• row 4 print (5-row)spaces, (2row - 1) stars
  
• row 5 print (5-row)spaces, (2row - 1) stars
  
• Algorithm for lower half
• row 4 print (5-row)spaces, (2row - 1) stars
  
• row 3 print (5-row)spaces, (2row - 1) stars
  
• row 2 print (5-row)spaces, (2row - 1) stars
  
• row 1 print (5-row)spaces, (2row - 1) stars
  

15
Diamond Pattern

• int row, space, star
• for(row1 rowlt5 row) //top half
• for(space1 spacelt5-row space)
• cout ltlt " "
• for(star1 starlt2row-1 star)
• cout ltlt ""
• cout ltlt endl
• for(row4 rowgt1 row--) //bottom half
• for(space1 spacelt5-row space)
• cout ltlt " "
• for(star1 starlt2row-1 star)
• cout ltlt ""
• cout ltlt endl