daily notes[3]

perl notes

1. typing perl program_name on the terminal can run a perl program(script) named program_name.
2. the following set of codes was replaces by use v5.35; at the 5.35 version or more than it.

use strict;
use warnings; 

3. annotation in perl language is flaged as # immediately before annotated content.
4. print funtion achieves the ouput task ,for example,print "hello,world".
5. $ closely followed by variable name illustrates that is a scalar variable such as $x,$y and so on.my keyword is used to declare a variable such as my $x=11;
6. @ indicates the following variable is array. for example:

my @nums=(11,22,33);
print $nums[0];

by the way,$#nums represent the index of last element in nums array.
7. % used to denote the definition of hash .

my %nums = ("one", 1, "two", 2);

my %fruit_color = (one  => 1,two => 2,
);

get value through the key in hash can use the following code.

$fruit_color{"two"};

8. the if statement constructs mutiple conditions flow.

if ( condition1 ) {...
} elsif ( condition2 ) {...
} else {...
}

references

1. https://www.perl.org/docs.html