subroutines and functions in perl-IGI

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In Perl, a subroutine is a block of code that can be called from within a program. Subroutines are used to group related code together and make the code more modular and reusable. A Perl subroutine can be defined using the sub keyword, followed by the name of the subroutine, the list of parameters (if any), and the block of code to be executed.

Here's an example of a simple subroutine in Perl:

sub greet {
    my $name = shift;
    print "Hello, $name!\n";
}

greet("John");

In this example, the greet subroutine is defined using the sub keyword. The shift function is used to get the first argument passed to the subroutine, which is assigned to the scalar variable $name. The print statement within the subroutine block prints a greeting message using the value of $name. The subroutine is then called with the argument "John", which is passed to the $name parameter. This results in the message "Hello, John!" being printed to the screen.

Functions in Perl are similar to subroutines, but they return a value when called. A Perl function is defined using the same syntax as a subroutine, but with a return statement at the end of the block of code to return a value.

Here's an example of a simple function in Perl:

sub add {
    my ($x, $y) = @_;
    return $x + $y;
}

my $result = add(3, 4);
print "3 + 4 = $result\n";

In this example, the add function is defined to take two arguments, which are assigned to the scalar variables $x and $y. The return statement within the function block returns the sum of $x and $y. The function is then called with the arguments 3 and 4, and the returned value is assigned to the scalar variable $result. The print statement then prints the message "3 + 4 = 7" to the screen.

In Perl, subroutines and functions can be defined anywhere in the program, and they can be called from anywhere in the program. This makes it easy to write modular and reusable code. You can also pass arrays and hashes to subroutines and functions, and you can use references to modify them.

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subroutines and functions in perl