Lexical Variables

Variables declared with my inside a subroutine stay local to that subroutine.
lexical variable A lexical variable belongs to the block where it is declared.
                            bonus
                            bonus = 3 (default)bonus = 0bonus = 5
                        

                            lexical_variables.pl
                        
Replay: real traced execution (multi-file project)

                            use strict;
use warnings;

sub add_bonus {
    my ($base, $bonus) = @_;
    my $inside_total = $base + $bonus;
    return $inside_total;
}

my $base = 10;
my $bonus = 3;
my $result = add_bonus($base, $bonus);

print "base=$base\n";
print "bonus=$bonus\n";
print "result=$result\n";
use strict;
use warnings;

sub add_bonus {
    my ($base, $bonus) = @_;
    my $inside_total = $base + $bonus;
    return $inside_total;
}

my $base = 10;
my $bonus = 0;
my $result = add_bonus($base, $bonus);

print "base=$base\n";
print "bonus=$bonus\n";
print "result=$result\n";
use strict;
use warnings;

sub add_bonus {
    my ($base, $bonus) = @_;
    my $inside_total = $base + $bonus;
    return $inside_total;
}

my $base = 10;
my $bonus = 5;
my $result = add_bonus($base, $bonus);

print "base=$base\n";
print "bonus=$bonus\n";
print "result=$result\n";

                        
1$base ← 10, $bonus ← 3⋯10my $base→ 10 = 10;11my $bonus→ 3 = 3; #@bonus=0, 512my $result = add_bonus($base10, $bonus3);⋯
2$base ← 10, $bonus ← 3, $inside_total ← 13⋯4sub add_bonus {5    my ($base→ 10, $bonus→ 3) = @_;6    my $inside_total→ 13 = $base10 + $bonus3;7    return $inside_total13;8}⋯
3$result ← 13⋯11my $bonus = 3; #@bonus=0, 512my $result→ 13 = add_bonus($base10, $bonus3);1314print "base=$base10\n";15print "bonus=$bonus3\n";16print "result=$result13\n";⋯outputbase=10
bonus=3
result=13
1$base ← 10, $bonus ← 0⋯10my $base→ 10 = 10;11my $bonus→ 0 = 0;12my $result = add_bonus($base10, $bonus0);⋯
2$base ← 10, $bonus ← 0, $inside_total ← 10⋯4sub add_bonus {5    my ($base→ 10, $bonus→ 0) = @_;6    my $inside_total→ 10 = $base10 + $bonus0;7    return $inside_total10;8}⋯
3$result ← 10⋯11my $bonus = 0;12my $result→ 10 = add_bonus($base10, $bonus0);1314print "base=$base10\n";15print "bonus=$bonus0\n";16print "result=$result10\n";⋯outputbase=10
bonus=0
result=10
1$base ← 10, $bonus ← 5⋯10my $base→ 10 = 10;11my $bonus→ 5 = 5;12my $result = add_bonus($base10, $bonus5);⋯
2$base ← 10, $bonus ← 5, $inside_total ← 15⋯4sub add_bonus {5    my ($base→ 10, $bonus→ 5) = @_;6    my $inside_total→ 15 = $base10 + $bonus5;7    return $inside_total15;8}⋯
3$result ← 15⋯11my $bonus = 5;12my $result→ 15 = add_bonus($base10, $bonus5);1314print "base=$base10\n";15print "bonus=$bonus5\n";16print "result=$result15\n";⋯outputbase=10
bonus=5
result=15