Quiz Examine the following block of code: sub bar { ($a,$b)=@_; $b=100; $a=$a+1; } sub foo { my($a)=67; local($b)=@_; bar($a, $b); } foo(5,10)
| 1: | After you run bar($a, $b) , what is the value in $b ? | | 2: | What is the return value from foo() ? | | 3: | Inside foo() , how is $b scoped? | Answers | A1: | b. $b is declared with local in foo() so that every called subroutine shares the same value for $b (unless they later declare $b again with local or my ). After calling bar() , where $b is modified, $b is set to 100. | | A2: | b. Surprised? The last statement in foo() is bar($a, $b) . bar() returns 68 because the value of $a is passed to bar() , and it's incremented. foo() returns the value of the last expression, which is 68. | | A3: | b. Variables declared with local are called dynamically scoped variables. | Activities -
Use the functions from the statistics exercise in this hour and the word-counting code from Hour 7, "Hashes," to examine the length of the words in a document. Compute their mean, median, and standard deviation. -
Write a function to print part of the Fibonacci series. This series begins 0, 1, 1, 2, 3, 5, 8 and continues forever. The Fibonacci series is a recurring pattern in mathematics and nature. Each successive number is the sum of the previous two (except 0 and 1). These numbers can be computed iteratively or recursively. |
