Learning notes for Perl-Chapter 3 1

Learning notes for Perl-Chapter 3 1

This article mainly introduces some arrays and lists, allowing you to fully understand the convenience and strength of Perl :)

Array:

1. The array is counted from 0.

2. Calculate the index value of the last element: $ # Rocks

3. Simply calculate the value of the last number: rocks [-1]

 

The range operator is used to indicate the direct quantity of the list:

(1. 5): 1, 2, 3, 4, 5

(5.7 ..): indicates that 1, 2, 3, 4, 5 decimal places are removed.

(): Empty list, only online count allowed

 

QW:

QW/Fred Barney Betty Wilma Dino /;

QW {

/Usr/local/words

/Home/rootbeer/. ispell_english

}

The QW operator can be used to easily define the list, and the front and back operators can be defined by themselves.

 

List assignment:

($ Fred, $ Barney, $ Dino) = ("Flintstone", "rubble", UNDEF );

Variable transformation method:

($ Fred, $ Barney) = ($ Barney, $ Fred );

Array assignment:

@ Rocks = QW/bedrock slate lava /;

Array replication:

@ Rocks = @ copy

 

Pop and push operators:

The pop function extracts the last element of an array and returns it:

@ Array = 5 .. 9;

$ Fred = POP (@ array); # $ Fred Get 9, @ array now has)

$ Fred = pop @ array; # $ Fred gets 8. Don't use the same brackets. @ array now has (, 6, 7)

The push function adds an element at the end of the array.

Push (@ array, 0); # Now @ array has (5, 6, 7, 0)

Push @ array, 8; # Now @ array has (5, 6, 7, 0, 8)

Push @ array, 1 .. 10; # @ array with 10 new elements added

Shift and unshift functions:

Operate on the beginning of the array, similar to pop and push;

@ Array = QW # Dino Fred Barney #;

$ A = shift (@ array); # $ A get Dino, @ array now ("Fred", "Barney ");

Unshift @ array, 4; # @ array now has 4, Fred, barney