Learning Perl, 4th Edition Notes 0x1

Learning Perl, 4th Edition Notes 0x1 by DaNmarner * Perl computes with double-precision floating-point values. * Octal (base 8) is leaded by 0, while hexadecimal leaded by 0x and binary 0b. * For clarity, underscore within integer literals is available. So is for non-decimal literals. * Use perl string to create, scan, and manipulate raw binary data. * Unlike in double quote, any characters other than a single quote or a backslash between the single quote marks stands for itself inside a string. * Numeric Operater: +-*/% String Operater: .x * Using Build-In Warnings Turn on in command line:

$perl -w program

or, for more details:

$perl -Mdiagnostics ./program

Request on #! line:

#!/usr/bin/perl use progma

#!/usr/bin/perl use warnings;

or, for more details:

#!/usr/bin/perl use digonostics;

* Output with print

print list;

list is a series of scalars seperated by commas. * Double-quoted string literal is subject to variable interpolation. Curly braces can be used as the delimiter of variable names. For instance:

print "This is $whats"; #print the value of $whats print "This is ${what}s" #print the value of $what

* Perl has the same precedence and associativity as C. * Numeric and string comparison operators: == eq (equel) != ne (not equel) <> gt (greater than) <= le (less or equel) >= ge (greater or equel) * For boolean values, 0 or empty string means false, other number or string means true; * reads the next complete text line from standard input. New line included. * Use chomp to remove the newline character from a string, common used like this: chomp ($line=); * The value undef exists in those unassigned variables. returns undef is there's no more input is there(end-of-file or Ctrl+D).