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Lists are stored in Perl array variables, and unlike simple variables, Perl array variables start with the character "@", such as: @ array= (1 ~ 2).

Perl array-storage of lists

Lists are stored in Perl array variables, which, unlike simple variables, start with the character "@", such as:

@ array= (1pm 2pm 3)

Note:

(1) when the Perl array variable is created, the initial value is an empty list: ().

(2) because PERL uses @ and $to distinguish between Perl array variables and simple variables, the same name can be used for both Perl array variables and simple variables, such as:

$var=1

@ var= (11pr 27.1, "astring")

But this is easy to confuse, so it is not recommended.

1. Access to Perl array

◆ accesses the values in the Perl array by subscript, with * elements subscribed to 0. If you try to access an element of the Perl array that does not exist, the result is NULL, but if you assign a value to an element that exceeds the size of the Perl array, the Perl array grows automatically, and the element value that did not exist is NULL. Such as:

@ array= (1, 2, 3, 4)

$scalar=$array [0]

$array [3] = 5witch now known arrayis (1meme 2pyrm 3pr 5)

$scalar=$array [4]; # now$scalar=null

$array [6] = 17 *

◆ Perl inter-array copy

@ result=@original

◆ uses the Perl array to assign values to the list

@ list1= (2, 3, 4)

@ list2= (1 recorder list1 penny 5); # @ list2= (1 recorder 2 minus 3 meme 4 rep 5)

Assignment of simple variables by ◆ Perl Array

(1) @ array= (5pm 7pm 11)

($var1,$var2) = @ array;#$var1=5,$var2=7,11 ignored

(2) @ array= (5pc7)

($var1,$var2,$var3) = @ array;#$var1=5,$var2=7,$var3= "" (null)

◆ assigns values to variables from standard input (STDIN)

$var=

@ array=;# ^ D is the symbol entered at the end

2. Square brackets and variable substitution in a string

"$var [0]" is the * * elements of the Perl array @ var.

"$var\ [0]" escapes the character "[" equivalent to "$var". "[0]", $var is replaced by a variable, and [0] remains the same.

"${var} [0]" is also equivalent to "$var". "[0]".

"$\ {var}" removes the variable substitution function of curly braces, including the text: ${var}.

3. List range:

(1) (1) (1) (1) (1) (1) 2) 3, 4, 5, 6, 7, 8, 9)

(2, 5... 7, 11) = (2, 5, 6, 7, 11)

(3. 3) = (3)

◆ is used for real numbers

(2.1... 5.3) = (2.1, 3.1, 4.1, 5.1)

(4.5.. 1.6) = ()

◆ is used for strings

("aaa".. "aad") = ("aaa", "aab", "aac", "aad")

@ day_of_month= ("01".. "31")

◆ can contain variables or expressions

($var1..$var2+5)

◆ Tips:

$fred= "Fred"

Print (("Hello,". $fred. "!\ n") x2)

The result is:

Hello,Fred!

Hello,Fred!

4. Output of Perl array:

(1) @ array= (1pm 2pm 3)

Print (@ array, "\ n")

The result is:

one hundred and twenty three

(2) @ array= (1pm 2pm 3)

Print ("@ array\ n")

The result is:

one hundred and twenty three

5. The length of the list / Perl array

When a Perl array variable appears where a simple variable is expected, the PERL interpreter takes its length.

@ array= (1pm 2pm 3)

$scalar=@array;#$scalar=3, which is the length of @ array

($scalar) = @ array;#$scalar=1, that is, the value of @ array***

Note: the length of the Perl array as the number of cycles can be programmed as follows:

$count=1

While ($count

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