How to store lists in Perl array
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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
