Perl Quick Guide. Perl - Quick Guide. Perl - Introduction. Perl is a general- purpose programming language originally developed for text manipulation and now used for a wide range of tasks including system administration, web development, network programming, GUI development, and more. What is Perl? Perl is a stable, cross platform programming language. Though Perl is not officially an acronym but few people used it as Practical Extraction and Report Language. It is used for mission critical projects in the public and private sectors. NAME; DESCRIPTION; Part 1: The basics. Simple word matching; Using character classes; Matching this or that; Grouping things and hierarchical matching. Regular Expressions in Perl. As you can see, you can seek a regex expression stored in a variable, and you can retrieve the result in $1. Sometimes PREG. Object Oriented Programming in Perl; Where is Perl used? The power of Perl can be implemented in many fields. The most popular use of Perl is in Web development. Perl is an Open Source software, licensed under its Artistic License, or the GNU General Public License (GPL). Perl was created by Larry Wall. Start of String and End of String Anchors. Thus far, we have learned about literal characters, character classes, and the dot. Putting one of these in a regex tells. A general introduction to Perl 6 programming aimed at newcomers to the Perl family of languages. Learn how to file test operators to tell if a file exists in Perl. NAME DESCRIPTION. Operator Precedence and Associativity Terms and List Operators (Leftward) The Arrow Operator Auto-increment and Auto-decrement. Perl 1. 0 was released to usenet's alt. At the time of writing this tutorial, the latest version of perl was 5. Perl is listed in the Oxford English Dictionary. PC Magazine announced Perl as the finalist for its 1. Technical Excellence Award in the Development Tool category. Perl Features. Perl takes the best features from other languages, such as C, awk, sed, sh, and BASIC, among others. Perls database integration interface DBI supports third- party databases including Oracle, Sybase, Postgres, My. SQL and others. Perl works with HTML, XML, and other mark- up languages. Perl supports Unicode. Perl is Y2. K compliant. Perl supports both procedural and object- oriented programming. Perl interfaces with external C/C++ libraries through XS or SWIG. Check If String Is Empty In Perl StringCheck If String Is Empty In Perl ScriptPerl is extensible. There are over 2. Comprehensive Perl Archive Network (CPAN). The Perl interpreter can be embedded into other systems. Perl and the Web. Perl used to be the most popular web programming language due to its text manipulation capabilities and rapid development cycle. Perl is widely known as . When you run a Perl program, it's first compiled into a byte code, which is then converted ( as the program runs) into machine instructions. So it is not quite the same as shells, or Tcl, which are strictly interpreted without an intermediate representation. It is also not like most versions of C or C++, which are compiled directly into a machine dependent format. It is somewhere in between, along with Python and awk and Emacs . Perl - Environment. Try it Option Online. We have set up the Perl Programming environment online, so that you can compile and execute all the available examples online. It gives you confidence in what you are reading and enables you to verify the programs with different options. Feel free to modify any example and execute it online. Try the following example using our online compiler available at Coding. Ground. #!/usr/bin/perl. This will print . So just make use of it and enjoy your learning. Before we start writing our Perl programs, let's understand how to setup our Perl environment. Perl is available on a wide variety of platforms . Just try giving the following command at the $ prompt . You need to download only the binary code applicable for your platform and install Perl. If the binary code for your platform is not available, you need a C compiler to compile the source code manually. Compiling the source code offers more flexibility in terms of choice of features that you require in your installation. Here is a quick overview of installing Perl on various platforms. Unix and Linux Installation. Here are the simple steps to install Perl on Unix/Linux machine. Open a Web browser and go to https: //www. Follow the link to download zipped source code available for Unix/Linux. Download perl- 5. Once installation is done, you can issue perl - v command at $ prompt to check perl installation. If everything is fine, then it will display message like we have shown above. Windows Installation. Here are the steps to install Perl on Windows machine. Follow the link for the Strawberry Perl installation on Windows http: //strawberryperl. Download either 3. Run the downloaded file by double- clicking it in Windows Explorer. This brings up the Perl install wizard, which is really easy to use. Just accept the default settings, wait until the installation is finished, and you're ready to roll! Macintosh Installation. In order to build your own version of Perl, you will need 'make', which is part of the Apples developer tools usually supplied with Mac OS install DVDs. You do not need the latest version of Xcode (which is now charged for) in order to install make. Here are the simple steps to install Perl on Mac OS X machine. Open a Web browser and go to https: //www. Follow the link to download zipped source code available for Mac OS X. Download perl- 5. You can do this from Unix, DOS, or any other system, which provides you a command- line interpreter or shell window. All you need is a GUI application on your system that supports Perl. You can download Padre, the Perl IDE. You can also use Eclipse Plugin EPIC - Perl Editor and IDE for Eclipse if you are familiar with Eclipse. Before proceeding to the next chapter, make sure your environment is properly setup and working perfectly fine. If you are not able to setup the environment properly then you can take help from your system admininstrator. All the examples given in subsequent chapters have been executed with v. Cent. OS flavor of Linux. Perl - Syntax Overview. Perl borrows syntax and concepts from many languages: awk, sed, C, Bourne Shell, Smalltalk, Lisp and even English. However, there are some definite differences between the languages. This chapter is designd to quickly get you up to speed on the syntax that is expected in Perl. A Perl program consists of a sequence of declarations and statements, which run from the top to the bottom. Loops, subroutines, and other control structures allow you to jump around within the code. Every simple statement must end with a semicolon (; ). Perl is a free- form language: you can format and indent it however you like. Whitespace serves mostly to separate tokens, unlike languages like Python where it is an important part of the syntax, or Fortran where it is immaterial. First Perl Program. Interactive Mode Programming. You can use Perl interpreter with - e option at command line, which lets you execute Perl statements from the command line. Let's try something at $ prompt as follows . Before you execute your script, be sure to change the mode of the script file and give execution priviledge, generally a setting of 0. They are only required occasionally to clarify the issues of precedence. Following two statements produce the same result. There are several programs available for every type of platform. There are many programs designd for programmers available for download on the web. As a Perl convention, a Perl file must be saved with a . PL file extension in order to be recognized as a functioning Perl script. File names can contain numbers, symbols, and letters but must not contain a space. Use an underscore (. Comments can be used to make program user friendly and they are simply skipped by the interpreter without impacting the code functionality. For example, in the above program, a line starting with hash # is a comment. Simply saying comments in Perl start with a hash symbol and run to the end of the line . Following is the example . Following program works perfectly fine . For example . A line containing only whitespace, possibly with a comment, is known as a blank line, and Perl totally ignores it. Single and Double Quotes in Perl. You can use double quotes or single quotes around literal strings as follows . Only double quotes interpolate variables and special characters such as newlines \n, whereas single quote does not interpolate any variable or special character. Check below example where we are using $a as a variable to store a value and later printing that value . Even you can make use of variables inside the . Below is a simple syntax, check carefully there must be no space between the < < and the identifier. An identifier may be either a bare word or some quoted text like we used EOF below. If identifier is quoted, the type of quote you use determines the treatment of the text inside the here docoment, just as in regular quoting. An unquoted identifier works like double quotes. For example value of a = $a. For example value of a = $a. For example value of a = 1. This is case of single quote so variable value will be. For example value of a = $a. Escaping Characters. Perl uses the backslash (\) character to escape any type of character that might interfere with our code. Let's take one example where we want to print double quote and $ sign . A Perl variable name starts with either $, & commat; or % followed by zero or more letters, underscores, and digits (0 to 9). Perl does not allow punctuation characters such as & commat; , $, and % within identifiers. Perl is a case sensitive programming language. The Perl interpreter will choose the type based on the context of the data itself. Perl has three basic data types: scalars, arrays of scalars, and hashes of scalars, also known as associative arrays. Here is a little detail about these data types. S. No. Types & Description. Scalar. Scalars are simple variables. They are preceded by a dollar sign ($). A scalar is either a number, a string, or a reference. A reference is actually an address of a variable, which we will see in the upcoming chapters. Arrays. Arrays are ordered lists of scalars that you access with a numeric index, which starts with 0. They are preceded by an . They are preceded by a percent sign (%). Numeric Literals. Perl stores all the numbers internally as either signed integers or double- precision floating- point values. Numeric literals are specified in any of the following floating- point or integer formats . They are usually alphanumeric values delimited by either single (') or double (. They work much like UNIX shell quotes where you can use single quoted strings and double quoted strings. Double- quoted string literals allow variable interpolation, and single- quoted strings are not. Accepted delimiters: white spaces (space, tab, new line etc.) and commas. You can use either simple (') or double (.
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