Conditional Operator

1
Conditional Operator

• A Shortcut for Certain Simple Decisions

2
Conditional Operator

• Symbol is ?
• Only ternary operator in C / C
• three operands
• all other operators are unary or binary
• Provides a shortcut for a common programming
  situation

3
Common Situation

• Traditional approach, using if statement
• if (firstVal lt secondVal)
• result firstVal
• else
• result secondVal
• Alternative approach, using conditional operator
• result (firstVal lt secondVal) ? firstVal
  secondVal

4
Structure of Statement Using Conditional Operator

• result (firstVal lt secondVal) ? firstVal
  secondVal
• test expression first
  second
• expression expression
• parentheses around test expression are optional
  but useful
• commonly necessary to put parentheses around the
  whole conditional expression (depending on use
  and precedence)

5
Execution of a Statement that Uses the Conditonal
Operator

• Evaluates the test expression
• If true, statement takes on the value of the
  first expression
• If false, statement takes on the value of the
  second expression
• Note the entire conditional expression takes on
  the value of first expression or second
  expression
• Conditional expression can be used anywhere that
  the value of the specified type can be used

6
Examples of Conditional Operator

• Example 1
• totPay hourlyRate ((hoursWorked lt 40) ?
• hoursWorked hoursWorked 1.1)
• Example 2
• write out the numbers from 1 to 60 at five per
  line
• for (int j 1 j lt 60 j)
• cout ltlt setw(3) ltlt j ltlt ((j 5) ? " " "
  \n")