Introduction to Programming

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Introduction to Programming

• Lecture No. 8

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In the last lecture

• Loops
• While
• Do while
• For
• Operators
• Increment / Decrement
• Compound Assignment Operators

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Example Program to calculate the average marks
of class

• int sum
• int students
• int average
• sum 0
• students 0
• do
• cin gtgt grade
• sum grade
• students
• while (grade gt 0)
• average sum / students
• cout ltlt average

A Flaw in the code
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• Multi-way decision

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if Statements

• if ( grade A )
• cout ltlt Excellent
• if ( grade B )
• cout ltlt Very Good
• if ( grade C )
• cout ltlt Good
• if ( grade D )
• cout ltlt Poor
• if ( grade F )
• cout ltlt Fail

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if else

• if ( grade A )
• cout ltlt Excellent
• else
• if ( grade B )
• cout ltlt Very Good
• else
• if ( grade C )
• cout ltlt Good
• else
• if ( grade D )
• cout ltlt Poor

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if else

• if ( grade A )
• cout ltlt Excellent
• else if ( grade B )
• else if
• else

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• switch statement

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switch statements

• switch ( variable name ) case a
  statements case b statements
• case c statements

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switch statements

• switch ( grade) case A cout ltlt
  Excellent case B cout ltlt Very Good
  case C

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switch statements

• case A
• cout ltlt Excellent

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Example

• switch ( grade)
• case A cout ltlt Excellent case B
  cout ltlt Very Good case C
• cout ltlt Good
• case D cout ltlt Poor case F
  cout ltlt Fail

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• break

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Example

• switch ( grade )
• case A
• cout ltlt Excellent
• break case B cout ltlt Very Good
• break case C
• cout ltlt Good
• break
• case D cout ltlt Poor
• break case F cout ltlt Fail
• break

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default

• default
• cout ltlt Please Enter Grade from A to D or
  F

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Flow Chart of switch statement
switch (grade)
case A
Display Excellent
case B
Display Very Good

Default
..
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• if ( amount gt 2335.09 ) statements

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Whole Number

• short
• int
• long

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• case A
• case 300
• case f

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break

• if (c z )
• cout ltlt Great ! You have made the correct
  guess break

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• continue

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continue

• while trynum lt 5
• .
• .
• continue

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continue in for loop

• for ( counter 0 counter lt 10 counter )
• .
• continue

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What have we done till now

• Sequential Statements
• Decisions
• if , if else , switch
• Loops
• while , do while , for

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• goto
• Unconditional Branch of Execution

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Structured Programming

• Sequences
• Decisions
• Loops

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• Minimize the use of break
• Minimize the use of continue
• Never use goto

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Guide lines for structured programming

• Modular
• Single entry - single exit

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Rules for Structured Flowchart

• Rule 1 Use the simplest flowchart
• Rule 2 Any rectangle can be replaced by
  two rectangles.
• Rule 3 Any rectangle can be replaced with
• structured flowcharting constructs.
  
• Rule 4 It says, rule 2 and rule 3 can be
• repeated as many times as needed

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Next Milestones

• Data Structures
• Arrays
• Character Strings
• Pointers