COMP 110 If Else and Case Statements

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COMP 110If / Else and Case Statements

• Tabitha Peck M.S.
• February 4, 2008
• MWF 3-350 pm
• Philips 367

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Announcements

• New Homework Policy
• Incorrect submissions lose a letter grade
• Three incorrect submissions zero credit
• Check .jar files BEFORE you send them
• See me if you are still having problems
• Grades
• Lab 1, Lab 2, Project 1
• Posting Grades online?
• Handing back grades?

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Questions?

• From Lab 2
• No real problems
• Never got the same problem twice

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Gotcha

• var1 var2 (assignment statement)
• Error!!!!!!!
• var1 var2 (boolean expression)
• Do NOT use to compare Strings
• string1 string2 //BAD
• string1.equals(string2) //GOOD

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Gotcha (Syntax)

• if (boolean expression)

DO NOT DO THIS!!!!!!!
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Today in COMP 110

• More if / else statements
• Case statements

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Tracing if / else code

• I give you code and input
• You give me output

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Example

• input 5? input 6?
• int days 0
• if (input lt 6)
• System.out.print(I worked input days
  this week)
• else
• days 6 input 1
• System.out.print(I worked days days
  of overtime)

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Another Example

• Write the if/else part of a program that
  determines if a person is old enough to vote
  based on their age. If the person is old enough
  to vote, ask if they are voting in the democrat
  or republican primary, and then if they are
  voting for Obama or Clinton, or McCain or Romney.

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Switch Statements

• switch (numOfSiblings)
• case 0
• System.out.print(An only child) break
• case 1
• System.out.print(Just one you say) break
• case 2
• System.out.print(Two siblings!) break
• case 3
• System.out.print(Big family!) break
• default
• System.out.print(I dont believe you)
  break

Controlling expression integer or char ONLY!
Case label
Break statement
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Practice with Switch statements

• Write a switch statement that takes as
  controlling expression your year in college (as
  in int) and outputs your year in college as
  freshman, sophomore, junior, senior, or super
  senior

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Shorthand for if / else

• if (n1 gt n2 )
• max n1
• else
• max n2
• max (n1 gt n2) ? n1 n2

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Wednesday

• Read 3.2
• Loop Statements

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