What is Perl | my keyword?

In this article, we will learn Perl | my keyword,This free Perl tutorial for complete beginners will help you learn Perl from scratch.

Perl | my keyword - ❤️Perl Tutorials In 2024

my keyword in Perl declares the listed variable to be local to the enclosing block in which it is defined. The purpose of my is to define static scoping. This can be used to use the same variable name multiple times but with different values.

Note: To specify more than one variable under my keyword, parentheses are used.

Syntax: my variable

Parameter:
variable: to be defined as local

Returns:
does not return any value.

Example 1:

#!/usr/bin/perl -w 
  
# Local variable outside of subroutine 
my $string = "Beginner for Beginner"; 
print "$string\n"; 
  
# Subroutine call 
my_func(); 
print "$string\n"; 
  
# defining subroutine  
sub my_func 
{ 
    # Local variable inside the subroutine 
    my $string = "This is in Function"; 
    print "$string\n"; 
    mysub(); 
} 
  
# defining subroutine to show 
# the local effect of my keyword 
sub mysub  
{ 
    print "$string\n"; 
} 

Output:

Beginner for Beginner
This is in Function
Beginner for Beginner
Beginner for Beginner

Example 2:

#!/usr/bin/perl -w 
  
# Local variable outside of subroutine 
my $string = "Welcome to Beginner"; 
print "$string\n"; 
  
# Subroutine call 
my_func(); 
print "$string\n"; 
  
# defining subroutine  
sub my_func 
{ 
    # Local variable inside the subroutine 
    my $string = "Let's GO Geeky!!!"; 
    print "$string\n"; 
    mysub(); 
} 
  
# defining subroutine to show 
# the local effect of my keyword 
sub mysub  
{ 
    print "$string\n"; 
} 

Output:

Welcome to Beginner
Let's GO Geeky!!!
Welcome to Beginner
Welcome to Beginner

How to define dynamic scoping?
The opposite of “my” is “local”. The local keyword defines dynamic scoping.

# A perl code to demonstrate dynamic scoping  
$x = 10;  
sub f  
{  
   return $x;  
}  
sub g  
{  
   # Since local is used, x uses    
   # dynamic scoping.  
   local $x = 20;  
  
   return f();  
}  
  
print g()."\n";  