Spell check and typos

perl/data-types/data-types.md

@@ -3,8 +3,8 @@ Perl is a loosely typed language and hence you no need to define the type of the
 Perl has three basic data types: 
 
 1. Scalars
-2. arrays 
-3. hashes 
+2. Arrays 
+3. Hashes 
 
 ## 1. Scalars
 

perl/hashes/hashes.md

@@ -1,6 +1,6 @@
 Hash is an unordered set of key/value pairs. They are preceded by `%`. 
 
-Array elements are accessed by using it's indices. But Hashes are accesed using it's descriptive keys.
+Array elements are accessed by using it's indices. But Hashes are accessed using it's descriptive keys.
 
 ## Example
 

perl/index.json

@@ -29,16 +29,6 @@
             }
         ]
     },
-    {
-        "title" : "Arrays",
-        "path" : "arrays",
-        "links" : [
-            {
-                "title" : "Arrays",
-                "path" : "arrays"
-            }
-        ]
-    },
     {
         "title" : "Strings",
         "path" : "strings",
@@ -69,6 +59,16 @@
             }
         ]
     },
+    {
+        "title" : "Arrays",
+        "path" : "arrays",
+        "links" : [
+            {
+                "title" : "Arrays",
+                "path" : "arrays"
+            }
+        ]
+    },
     {
         "title" : "Hashes",
         "path" : "hashes",
@@ -105,7 +105,7 @@
     },
     {
         "title" : "OOPS in Perl",
-        "path" : "oops",
+        "path" : "oops-in-perl",
         "links" : [
             {
                 "title" : "OOP Principles",

perl/introduction/introduction.md

@@ -1,5 +1,5 @@
 
-Perl(Practical Extraction and Report Language) is especially desined for text processing by Larry Wall. Perl is a high level programming language and hence one can easily undertand Perl as the programs are in simple english.
+Perl(Practical Extraction and Report Language) is especially designed for text processing by Larry Wall. Perl is a high level programming language and hence one can easily undertand Perl as the programs are in simple english.
 
 ## Key features
 * Cross-platform programming language
@@ -35,41 +35,41 @@ print "Hello World!!"; // to display "Hello World!!"
 3. Follow the installation steps to finish the setup.
 4. Once the installation is completed, check the installation by using the below command in command prompt. 
 
-```sh
-perl -v
-```
+    ```sh
+    perl -v
+    ```
 
 ## 2. On Linux
 1. Most Linux  modern Linux distributions come with a recent version of Perl. If not, you can download the software form [Perl Downloads](https://www.perl.org/get.html)
 2. Execute the below commands
-```sh
-tar -xzf perl-5.30.2.tar.gz
-cd perl-5.30.2
-$./Configure -de
-$make
-$make test
-$make install
-```
+    ```sh
+    tar -xzf perl-5.30.2.tar.gz
+    cd perl-5.30.2
+    $./Configure -de
+    $make
+    $make test
+    $make install
+    ```
 
 ### Note :
 Change the version based on the file you have downloaded in the above commands
 
 ## 3. On MacOS
 
-1. Recent MacOS come with a recent version of Perl. If not, you can download the software form [Perl Downloads](https://www.perl.org/get.html)
+1. Recent MacOS will have Perl installed in-built. If not, you can download the software form [Perl Downloads](https://www.perl.org/get.html)
 2. change the directory
-```sh
-cd ~/Downloads
-```
+    ```sh
+    cd ~/Downloads
+    ```
 3. Run the below commands
-```sh
-tar -xzf perl-5.30.2.tar.gz
-cd perl-5.30.2
-./Configure -de
-make
-make test
-make install
-```
+    ```sh
+    tar -xzf perl-5.30.2.tar.gz
+    cd perl-5.30.2
+    ./Configure -de
+    make
+    make test
+    make install
+    ```
 
 ### Note :
 Change the version based on the file you have downloaded in the above commands

perl/lists/lists.md

@@ -24,7 +24,7 @@ print("happy", 16) # prints happy16
 ```
 ### Check result [here](https://onecompiler.com/perl/3vnqnmnss)
 
-Lists are indexed like arrays and indices starts from zero, means list[0] refers to first element and to access nth element, you should list[n-1].
+Lists are indexed like arrays and indices starts from zero, means `list[0]` refers to first element and to access nth element, you should use `list[n-1]`.
 
 ```perl
 print((1,2,3,4,5)[0]); # to access first element

perl/oops-in-perl/oops.md

@@ -74,4 +74,4 @@ Encapsulation is a mechanism to protect private hidden data from other users. It
 
 Polymorphism gives the meaning many forms, usually it occurs when multiple classes are present and have been inherited.
 
-Consider an example of installing an application in your mobile, where your base class is `Mobile` and method is `installation()` and its derived classes could be installApp1, installApp2, installApp3 etc which will have its own implementation but installation method can be common which can be inherited from its base class.
+Consider an example of installing an application in your mobile, where your base class is `News` and method is `subscribeNews()` and its derived classes could be Sports, Politics, Business, Weather etc which will have its own implementation but the method `subscribeNews()` can be common which can be inherited from its base class.

perl/sub-routine/sub-routine.md

@@ -1,8 +1,9 @@
 Sub-routine is a function which contains set of statements. Usually they are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
 
-Sub-routine allows you to divide your large lines of code into smaller ones. Usually the division happens logically such that each function performs a specific task and is up to developer. You can define a sub-routine anywhere in you program. You can also use sub-routines defined in some other programs. `use`, `do` or `require` statements are used to load sub-routines defined in other programs.
+Sub-routine allows you to divide your large lines of code into smaller ones. Usually the division happens logically such that each function performs a specific task and is up to developer. You can define a sub-routine anywhere in your program. You can also use sub-routines defined in some other programs. `use`, `do` or `require` statements are used to load sub-routines defined in other programs.
 
-`eval()` function is used to generate a sub-routine at run-time. `sub` is the keyword used to define a sub-routine
+* `eval()` function is used to generate a sub-routine at run-time. 
+* `sub` is the keyword used to define a sub-routine
 
 ## How to define a sub-routine
 

perl/variables/variables.md

@@ -40,7 +40,7 @@ print "I love $fruits"
 ```
 ### Check result [here](https://onecompiler.com/perl/3vnmn3yty)
 
-You might expect the output as `I love mango` but you might be surprised to see the output as `I love`. This is because `fruit` and `fruits` are two different variables and `fruits` is not assigned with any value. To avoid these king of mistakes while programming, Perl provides a pragma called strict which requires you to declare variable explicitly before using the variable is used. `my` is used to declare variables when you use `strict`.
+You might expect the output as `I love mango` but you might be surprised to see the output as `I love` without throwing any error. This is because `fruit` and `fruits` are two different variables and `fruits` is not assigned with any value. To avoid these king of mistakes while programming, Perl provides a pragma called `strict` which requires you to declare variable explicitly before using the variable is used. `my` is used to declare variables when you use `strict`.
 
 The above example when you use `strict`
 

perl/working-with-databases/databases.md

@@ -8,23 +8,23 @@ In this chapter, let's learn how to interact with MySQL database in Perl.
 
 There are multiple ways to install MySQL drivers, one of the ways is by using `CPAN`.
 
-```sh
-perl -MCPAN -e shell
-```
+  ```sh
+  perl -MCPAN -e shell
+  ```
 * To install `DBD::mysql` use the below command,
 
-```sh
-install DBD:mysql
-```
+  ```sh
+  install DBD:mysql
+  ```
 * Installation progress can be seen in command prompt.
 
 ## How to connect to MySQL database server
 
 Consider we are creating  a sample database called `test`
 
-```sh
-my $dbh = DBI->connect("DBI:mysql:test",'root','');
-```
+  ```sh
+  my $dbh = DBI->connect("DBI:mysql:test",'root','');
+  ```
 
 DBI->connect has three parameters:
 1. Data  source name
@@ -36,52 +36,52 @@ DBI->connect returns false when the connection is not established.
 ## Insert data in to the database
 
 Once the connection is established, you can insert data into the tables. Consider you are inserting data into DATA_TABLE
-```perl
-my $sth = $dbh->prepare("INSERT INTO DATA_TABLE
-                       (NAME, ID, OCCUPATION )
-                         values
-                       ('foo', 123, 'doctor')");
-$sth->execute() or die $DBI::errstr;
-print "Inserted rows:" + $sth->rows;
-$sth->finish();
-$dbh->commit or die $DBI::errstr;
-```
+  ```perl
+  my $sth = $dbh->prepare("INSERT INTO DATA_TABLE
+                        (NAME, ID, OCCUPATION )
+                          values
+                        ('foo', 123, 'doctor')");
+  $sth->execute() or die $DBI::errstr;
+  print "Inserted rows:" + $sth->rows;
+  $sth->finish();
+  $dbh->commit or die $DBI::errstr;
+  ```
 
 ## Read data from tables
 
-```perl
-my $sth = $dbh->prepare("SELECT NAME, ID
-                        FROM DATA_TABLE 
-                        WHERE OCCUPATION = 'doctor'");
-$sth->execute() or die $DBI::errstr;
-print "Number of records whose occupation is doctor :" + $sth->rows;
-while (my @row = $sth->fetchrow_array()) {
-   my ($name, $id ) = @row;
-   print "Name = $name, ID = $id\n";
-}
-$sth->finish();
-```
+  ```perl
+  my $sth = $dbh->prepare("SELECT NAME, ID
+                          FROM DATA_TABLE 
+                          WHERE OCCUPATION = 'doctor'");
+  $sth->execute() or die $DBI::errstr;
+  print "Number of records whose occupation is doctor :" + $sth->rows;
+  while (my @row = $sth->fetchrow_array()) {
+    my ($name, $id ) = @row;
+    print "Name = $name, ID = $id\n";
+  }
+  $sth->finish();
+  ```
 
 ## Updating a record
 
-```perl
-my $sth = $dbh->prepare("UPDATE DATA_TABLE
-                        SET OCCUPATION = 'student' 
-                        WHERE ID = 123");
-$sth->execute() or die $DBI::errstr;
-print "Updated rows:" + $sth->rows;
-$sth->finish();
-$dbh->commit or die $DBI::errstr;
-```
+  ```perl
+  my $sth = $dbh->prepare("UPDATE DATA_TABLE
+                          SET OCCUPATION = 'student' 
+                          WHERE ID = 123");
+  $sth->execute() or die $DBI::errstr;
+  print "Updated rows:" + $sth->rows;
+  $sth->finish();
+  $dbh->commit or die $DBI::errstr;
+  ```
 
 ## Deleting a record
 
-```perl
-my $sth = $dbh->prepare("DELETE FROM DATA_TABLE
-                         WHERE ID = 123");
-$sth->execute( $id ) or die $DBI::errstr;
-print "Deleted rows:" + $sth->rows;
-$sth->finish();
-$dbh->commit or die $DBI::errstr;
-```
+  ```perl
+  my $sth = $dbh->prepare("DELETE FROM DATA_TABLE
+                          WHERE ID = 123");
+  $sth->execute( $id ) or die $DBI::errstr;
+  print "Deleted rows:" + $sth->rows;
+  $sth->finish();
+  $dbh->commit or die $DBI::errstr;
+  ```