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Solution Review: Fibonacci Sequence

Explore how to generate the Fibonacci sequence using Perl loops. This lesson walks you through initializing variables and using a for loop with conditions to build the sequence efficiently up to a defined range.

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Let’s look at the solution first before jumping into the explanation:

Perl
$range = 6;    # change range to print sequence till that point
$ans = "";
$first = 0; 
$second = 1;
$fibonacci = 0;
for ($c = 0 ; $c < $range ; $c++ )
{
  if ( $c <= 1 ){
    $fibonacci = $c;
    $ans .= $fibonacci . " ";
  }
  else{
    $fibonacci = $first + $second;
    $first = $second;
    $second = $fibonacci;
    $ans .= $fibonacci . " ";
  }
}
$ans =~ s/\s+$//;
print $ans;

Explanation

We have initialized the $range variable up to which we print the sequence. We run the for loop until this $range. In the first two iterations of the loop, we append the “0” and “1” in the if condition, and for every iteration onwards, we find $fibonacci by adding the previous two elements.