The presence of unused variables may indicate significant logic errors. To prevent such errors, unused values should be identified and removed from code.

Noncompliant Code Example

This noncompliant code example contains a variable $new_name that is initialized but never subsequently read.

sub fix_name {
  my $name = shift;
  my $new_name = $name;

  $name =~ s/^([a-z])/\U$1\E/g;
  $name =~ s/ ([a-z])/ \U$1\E/g;
  return $name;
}

Compliant Solution

This compliant solution eliminates the unused variable

sub fix_name {
  my $name = shift;

  $name =~ s/^([a-z])/\U$1\E/g;
  $name =~ s/ ([a-z])/ \U$1\E/g;
  return $name;
}

Risk Assessment

The presence of unused variables may indicate logic errors that can lead to unintended program behavior. As a result, resolving unused variables can be an in-depth process requiring significant analysis.

Related Guidelines

CERT C Secure Coding Standard: MSC13-C. Detect and remove unused values

CERT C++ Secure Coding Standard: MSC13-CPP. Detect and remove unused values

Automated Detection

Bibliography

[CPAN] Elliot Shank, Perl-Critic-1.116 Variables::ProhibitUnusedVariables