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Perl Fundamentals Copyright © 2003 ProsoftTraining. All rights reserved. Lesson 1: Introduction to Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • Describe the benefits of Perl • Explain the role of the Perl interpreter • Identify the characteristics of Perl’s basic syntax • Describe the use of the print function • Create and execute a simple Perl script • Define scalar variables • Use scalar variables to manipulate numerical and string data • Use expression operators • Retrieve data from STDIN Practical Extracting and Reporting Language • Why use Perl? – Innate flexibility – Simple syntax – Relaxed compiler instructions – Free Getting Started with Perl • The shebang line • Creating a simple Perl script Scalar and Numerical Variables • Assignment • Expressions String Variables • Second type of scalar variable • The print function Retrieving Data from STDIN • The chomp() function Summary Describe the benefits of Perl Explain the role of the Perl interpreter Identify the characteristics of Perl’s basic syntax Describe the use of the print function Create and execute a simple Perl script Define scalar variables Use scalar variables to manipulate numerical and string data Use expression operators Retrieve data from STDIN Lesson 2: Flow Control in Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • Evaluate Boolean expressions Construct an if statement Discuss else and elsif branches Construct a while loop, a do {} while loop, and a for loop • Use loop-control commands • Describe the I/O redirection paradigm Boolean Expressions in Perl • Numeric Boolean expressions • String Boolean expressions • Logical operators The if Statement • The else branch • The elsif branch The while Statement • Second type of control structure • Defines a block of code that will be executed repeatedly as long as some Boolean expression evaluates as true The do { } while Statement • Similar to the while loop except that the condition is not evaluated until the code block has already been executed once The for Statement • Includes three expressions separated by semicolons • Incorporates facilities for initializing a counter and incrementing it on each turn through the code block Loop-Control Commands • last • next • redo I/O Redirection • Many Perl scripts use I/O redirection in place of more complicated file-handling subroutines Summary Evaluate Boolean expressions Construct an if statement Discuss else and elsif branches Construct a while loop, a do {} while loop, and a for loop Use loop-control commands Describe the I/O redirection paradigm Lesson 3: Regular Expressions in Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • Define regular expressions • Perform pattern matching • Define and use metacharacters, quantifiers and assertions • Explain character classes • Perform substitution • Use the binding operator Introduction to Regular Expressions • Pattern binding operators • Escape sequences and metacharacters Character Classes • Indicate a list of characters that one element in a string will match Pattern Matching and Substitution • Back references Summary Define regular expressions Perform pattern matching Define and use metacharacters, quantifiers and assertions Explain character classes Perform substitution Use the binding operator Lesson 4: Arrays in Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • Describe the purpose of arrays Define arrays using lists Access array elements Use the sort function to sort an array alphabetically • Use a foreach loop to traverse an array • Use the push, pop, shift, unshift, split and join functions Introduction to Perl Arrays • Initializing arrays • Accessing array elements The sort Function • Accepts an array as an argument, alphabetizes the elements within the array, and returns the resultant array The foreach Statement • A special control structure designed to iterate through an array or list The push and pop Functions • The push function adds values to the top of a stack • The pop function removes values from a stack The shift and unshift Functions • The unshift function adds a value to the front of an array and shifts the rest of the array by one • The shift function removes values from an array • Using an array as a queue The split and join Functions • The split function accepts two arguments, a regular expression and a string • The join function accepts a list of values and combines them into a single string Summary Describe the purpose of arrays Define arrays using lists Access array elements Use the sort function to sort an array alphabetically Use a foreach loop to traverse an array Use the push, pop, shift, unshift, split and join functions Lesson 5: Hashes in Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • Describe the purpose of hashes Define hashes using lists Access hash elements Use the delete, keys, values, each, and reverse functions Introduction to Perl Hashes • Hashes are collections of scalar values that can be accessed individually • Hash elements are accessed using an arbitrary scalar value, called a key • Also known as associative arrays Adding and Deleting Hash Elements • • • • • The delete function The keys function The values function The each function The reverse function Summary Describe the purpose of hashes Define hashes using lists Access hash elements Use the delete, keys, values, each, and reverse functions Lesson 6: Subroutines in Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • • • Define and use a subroutine Call subroutines directly and indirectly Pass values to a subroutine Pass references to a subroutine Explain variable scope Return a value from a subroutine Introduction to Perl Subroutines • • • • • Defining subroutines Calling subroutines Passing arguments Returning values The sort function and subroutines Variable Scope • Variables can be created within subroutines that are private (specific) to just that subroutine using the my operator – The my operator takes a scalar, array, or hash name and instantiates local versions inside a subroutine References • Creating and referencing anonymous arrays • Creating and referencing anonymous hashes • Passing references to subroutines Summary Define and use a subroutine Call subroutines directly and indirectly Pass values to a subroutine Pass references to a subroutine Explain variable scope Return a value from a subroutine Lesson 7: File Input and Output Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • • • Define and use filehandles Obtain a filehandle using the open function Output data to a file Close a file using the close function Open a file for reading Use the stat and lstat functions to obtain information about a file Perl File Input and Output • • • • • • • What is a filehandle? The open function Outputting data to a file Opening files for reading Other file-related functions Determining information about files The stat and lstat functions Summary Define and use filehandles Obtain a filehandle using the open function Output data to a file Close a file using the close function Open a file for reading Use the stat and lstat functions to obtain information about a file Lesson 8: Environment Variables and Command Line Arguments Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • Access and use environment variables • Use command line arguments • Define options when handling command line arguments Environment Variables • What are environment variables? – Shells Command Line Arguments • Arguments entered at the command line can be used in Perl programs Summary Access and use environment variables Use command line arguments Define options when handling command line arguments Lesson 9: Packages and Modules in Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • • • Describe the purpose of packages Use the package keyword Use BEGIN and END blocks Describe the purpose of modules Create a module to facilitate code reuse Incorporate a module into your Perl scripts using the use and require statements • Use the Exporter module Using Packages in Perl • Namespace • The package keyword • Package symbol tables BEGIN and END Blocks • Special blocks of code defined within a package Using Modules in Perl • Specially designed Perl scripts that package functionality for reuse by other Perl scripts The use and require Statements • The require statement takes a single argument (the name of the module to include) • The use statement adds symbols directly to the including package’s symbol table Summary Describe the purpose of packages Use the package keyword Use BEGIN and END blocks Describe the purpose of modules Create a module to facilitate code reuse Incorporate a module into your Perl scripts using the use and require statements Use the Exporter module Lesson 10: Object-Oriented Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • • Describe the purpose of objects Define objects for use in your Perl scripts Access object data Define and use object methods Use inheritance to expand the functionality of a class Introduction to Object-Oriented Perl • Creating objects • Object data • Object methods Inheritance • @ISA array • Destructor methods Summary Describe the purpose of objects Define objects for use in your Perl scripts Access object data Define and use object methods Use inheritance to expand the functionality of a class Lesson 11: Database Connectivity and Perl Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • • • • • Define database programming Explain the benefits of using a database Define and use the DBI, the DBD, and SQL Open a database connection Query a database Return records from a database Insert records into a database Close a connection to a database Introduction to Database Connectivity • Database programming • Database Interface Module • Database Driver Module Interacting with Databases 1. Connect to the database 2. Query the database 3. Display the results 4. Close the connection Connecting to Databases • The connect method Structured Query Language • Data Definition Language – CREATE – DROP • Data Query Language • Data Manipulation Language – INSERT – DELETE – UPDATE Quoting Operators • Perl includes quoting operators that can be used instead of single or double quotation marks Summary Define database programming Explain the benefits of using a database Define and use the DBI, the DBD, and SQL Open a database connection Query a database Return records from a database Insert records into a database Close a connection to a database Lesson 12: Debugging Perl Programs Copyright © 2003 ProsoftTraining. All rights reserved. Objectives • • • • • • Debug Perl programs Use the –w switch Use the strict module Issue commands to the Perl debugger Trace the execution of a Perl script Design Perl scripts to minimize bugs Introduction to Debugging Perl Scripts • Using the print command • Using the –w switch • Using the strict module The Perl Debugger • Traps and fixes errors in a Perl script • An interactive Perl environment wherein the user is prompted for debugger commands Writing Bug-Free Perl Code • Preventing errors • Common Perl errors Summary Debug Perl programs Use the –w switch Use the strict module Issue commands to the Perl debugger Trace the execution of a Perl script Design Perl scripts to minimize bugs Perl Fundamentals Introduction to Perl Flow Control in Perl Regular Expressions in Perl Arrays in Perl Hashes in Perl Subroutines in Perl File Input and Output in Perl Perl Fundamentals Environment Variables and Command Line Arguments Packages and Modules in Perl Object-Oriented Perl Database Connectivity and Perl Debugging Perl Programs