1. List
A list is a sequence of values contained in parentheses, which can be any number, or empty, such as: (1, 5.3, "Hello", 2), empty list: ().
2. Arrays--Storage of lists
The list is stored in an array variable, and the array variable starts with the character "@", unlike the simple variable.
(1) When the array variable is created, the initial value is an empty list;
(2) The same name can be used for both named arrays and variables;
- Storage of arrays
- Subscript access, the first subscript is 0
- Copy between arrays, @result = @original
- The array is assigned to the list, @list2 = (1, @list1, 5); # @list2 = (1, 2, 3, 4, 5)
- The assignment of an array to a simple variable, @list2 = (1, @list1, 5); # @list2 = (1, 2, 3, 4, 5)
- Brackets and variable substitution in a string
- "$var [0]" is the first element of an array @var.
"$var \[0]" escapes the character "[", equivalent to "$var". "[0]", $var is replaced by a variable, [0] remains unchanged.
"${var}[0" is also equivalent to "$var". " [0] ".
"$\{var}" cancels the variable substitution function for curly braces, including text: ${var}.
- List range
- (1..10) = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
(2, 5..7, 11) = (2, 5, 6, 7, 11)
(3..3) = (3)
. For real numbers
(2.1..5.3) = (2.1, 3.1, 4.1, 5.1)
(4.5..1.6) = ()
. for string
("AAA" ... " AAD ") = (" AAA "," AaB "," AAC "," AAD ")
@day_of_month = ("01": " 31 ")
. Can contain a variable or an expression
($var 1.. $var 2+5)
. Tips:
$fred = "Fred";
Print ("Hello,". $fred. "!\n") x 2);
The result is:
Hello, fred!.
Hello, fred!.
- Output of the array
- @ary = {1, 2, 3};
- Print (@ary, "\ n"); #123
- Print ("@ary", "\ n"); #1 2 3
- List, length of array
- When an array variable appears where the expected simple variable appears, the Perl interpreter takes its length. $len = @ary;
- Sub-array
- @array = (1, 2, 3, 4, 5);
@subarray = @array [0,1]; # @subarray = (1, 2)
@subarray2 = @array [1..3]; # @subarray2 = (2,3,4)
- Library functions for arrays
- Sort sorted by character order
- Reverse Inverse array
- Chop Array to tail
- Join/split Connect/Split
List and array variables
