Getting started with the Perl language

Perl is an abbreviation for practical Extraction and report Language, which can be translated as a "utility statement extraction language".

Perl Syntax Basics:

(1) Perl programs consist of statements and statements

(2) Perl program execution from top to bottom

(3) The Perl statement ends with a semicolon (;), including statements such as circular judgments

(4) Perl does not have a strict format specification, it can be indented according to its preferred way

First Perl program:

(1) Interactive programming

Perl-e ' print ' Hellow, Wold "'

Use the-E option to execute Perl statements

(2) Script programming

The extension of a Perl script is a. pl or. pl and cannot contain spaces in the pin name

For example, write a simple script hello.pl as follows

 
 
1 #！/usr/bin/perl
2 
3 print "hello, wold";

The function of the code is to output the string "Hello, Wold", while #!/usr/bin/perl is the path to the Perl interpreter

Executing scripts in the terminal $perl hello.pl

Another way to execute a script is to have the script get executable permissions, chmod 0755 hello.pl (or chmod u+x hello.pl), and then./hello.pl Direct execution

Perl language Annotations:

(1) Single-line comment, #开头的行是注释行, will be ignored when executed

(2) Multi-line comments, beginning with =pod, =cut end, the middle part is the comment content, can be multiple lines, execution will be ignored. Perform the following example

1 #! / usr / bin / perl
  2 
  3 #This is a line of comments
  4
  5 = pod
  6 This is note 1
  7 This is note 2
  8 This is note 3
  9 = cut
10
11 print "hello, wold \ n";

White space in the Perl language:

(1) blank refers to space, blank line, tab, etc.

(2) The interpreter ignores the blank in the statement

 
print "hello, wold\n";
print              "hello, wold\n";
print
"hello, wold\n";

The above three pieces of code perform the same effect

Single and double quotation marks in the Perl language:

(1) Double quotes can parse some escape characters and variables normally

(2) Single quotes cannot be escaped

 
1 $a = 10;
2 print "a = $a\n";
3 print ‘b = $a\n‘;

The result of the output is:

 
1 a = 10
2 b = $a\n

Escaping in the Perl language:

(1) Perl relay uses backslashes \

Identifiers in the Perl language:

(1) Identifiers refer to the names of variables, constants, functions, and block of statements in a language

Getting started with the Perl language