Perl scalar

A scalar is a simple unit of data.

A scalar can be an integer, a floating point number, a character, a string, a paragraph, or a complete web page.

The following example demonstrates a simple use of scalars:

Example

#!/usr/bin/perl $age = 20 ; # Integer assignment $name = " Codercto " ; # string $salary = 130.50 ; # Floating point number print " Age = $age n " ; print " Name = $name n " ; print " Salary = $salary n " ;

Executing the above program, the output result is:

 Age = 20Name = CoderctoSalary = 130.5

numeric scalar

A scalar is usually a number or a string. The following examples demonstrate the use of different types of numeric scalars:

Example

#!/usr/bin/perl $integer = 200 ; $negative = - 300 ; $floating = 200.340 ; $bigfloat = - 1.2 E - 23 ; # octal 377, decimal 255 $octal = 0377 ; # Hexadecimal FF, decimal is 255 $hexa = 0 xff ; print " integer = $integer n " ; print " negative = $negative n " ; print " floating = $floating n " ; print " bigfloat = $bigfloat n " ; print " octal = $octal n " ; print " hexa = $hexa n " ;

Executing the above program, the output result is:

 integer = 200negative = -300floating = 200.34bigfloat = -1.2e-23octal = 255hexa = 255

string scalar

The following examples demonstrate the use of different types of string scalars. Pay attention to the difference between single quotes and double quotes:

Example

#!/usr/bin/perl $var = " String scalar - coder tutorial! " ; $quote = ' I am in single quotes - $var ' ; $double = " I am in double quotes - $var " ; $escape = " Escape characters are used - t Hello, World! " ; print " var = $var n " ; print " quote = $quote n " ; print " double = $double n " ; print " escape = $escape n " ;

Executing the above program, the output result is:

 var = String scalar - Programmer's Tutorial! quote = I'm in single quotes - $vardouble = I'm in double quotes - String scalar - Programmer's Tutorial! escape = Use escape characters - Hello, World!

Scalar operations

The following example demonstrates simple operations on scalars:

Example

#!/usr/bin/perl $str = " hello " . " world " ; # String concatenation $num = 5 + 10 ; # Add two numbers $mul = 4 * 5 ; # Multiply two numbers $mix = $str . $num ; # Concatenate strings and numbers print " str = $str n " ; print " num = $num n " ; print " mix = $mix n " ;

Executing the above program, the output result is:

 str = helloworldnum = 15mix = helloworld15

multiline string

We can use single quotes to output multi-line strings as follows:

Example

#!/usr/bin/perl $string = ' Coder Tutorial - Learn not only technology, but also dreams! ' ; print " $string n " ;

Executing the above program, the output result is:

 Tutorial for coders - learn not only technology, but also dreams!

You can also use the "here" document syntax to output multiple lines:

Example

#!/usr/bin/perl print << EOF ;Tutorial for coders--learn not only technology, but also dreams! EOF

Executing the above program, the output result is:

 Tutorial for coders - learn not only technology, but also dreams!

special characters

Below we will demonstrate the application of special characters in Perl, such as __FILE__, __LINE__, and __PACKAGE__, which respectively represent the file name, line number, and package name of the currently executing script.

Note : __ is two underscores, and there are two underscores before and after __FILE__ .

These special characters are separate tokens and cannot be written in a string, for example:

Example

#!/usr/bin/perl print " File name " . __FILE__ . " n " ; print " line number " . __LINE__ . " n " ; print " Package name " . __PACKAGE__ . " n " ; # Unable to parse print " __FILE__ __LINE__ __PACKAGE__ n " ;

Executing the above program, the output result is:

 File name test.pl line number 4 package name main__FILE__ __LINE__ __PACKAGE__

v string

A string starting with v followed by one or more integers separated by periods is treated as a string literal.

When you want to directly declare the numeric value for each character, v-string provides a cleaner way to construct such strings, unlike "x{1}x{14}x{ 12c}x{fa0}" is not easy to understand. We can look at the following examples:

Example

#!/usr/bin/perl $smile = v9786 ; $foo = v102 .111 .111 ; $martin = v77 .97 .114 .116 .105 .110 ; print " smile = $smile n " ; print " foo = $foo n " ; print " martin = $martin n " ;

Executing the above program, the output result is:

 Wide character in print at test.pl line 7.smile = ☺foo = foomartin = Martin