{"id":21976,"date":"2023-02-21T06:46:11","date_gmt":"2023-02-21T06:46:11","guid":{"rendered":"https:\/\/www.booksofall.com\/?post_type=product&p=21976"},"modified":"2023-02-21T06:46:29","modified_gmt":"2023-02-21T06:46:29","slug":"learning-perl-the-hard-way","status":"publish","type":"product","link":"https:\/\/www.booksofall.com\/fr\/learning-perl-the-hard-way\/","title":{"rendered":"Learning Perl The Hard Way"},"content":{"rendered":"

This chapter presents two of the built-in types, arrays and scalars. A scalar is a value that Perl treats<\/a> as a single unit, like a number or a word. An array is an ordered collection of elements, where the elements are scalars.<\/p>\n

This chapter describes the statements and operators you need to read commandline arguments, define and invoke subroutines, parse parameters, and read the contents of files. The chapter ends with a short program that demonstrates these features.<\/p>\n

In addition, the chapter introduces an important concept in Perl<\/a>: context.<\/p>\n

1.1 Echo<\/p>\n

The UNIX utility <\/a>called echo takes any number of command-line arguments and prints them. Here is a perl program that does almost the same thing: print @ARGV;<\/p>\n

The program contains one print statement. Like all statements, it ends with a semi-colon. Like all generalizations, the previous sentence is false. This is the first of many times in this book when I will skip over something complicated and try to give you a simple version to get you started. If the details are important later, we\u2019ll get back to them.<\/p>\n

The operand of the print operator is @ARGV. The \u201cat\u201d symbol indicates that @ARGV<\/a> is an array variable; in fact, it is a built-in variable that refers to an array of strings that contains whatever command-line arguments are provided when the program executes.<\/p>\n

There are several ways to execute a Perl program, but the most common is to put a \u201cshebang\u201d line at the beginning that tells the shell where to find the program called perl that compiles and executes Perl programs<\/a>. On my system, I typed whereis perl and found it in \/usr\/bin, hence<\/p>\n","protected":false},"excerpt":{"rendered":"