Larry all:
https://www.youtube.com/watch?v=JzIWdJVP-wo&NR=1
-- -----------------------------------------------
Lecture - 21 PERL - Part I
https://www.youtube.com/watch?v=1pVolaKhxVM&feature=PlayList&p=04D5787E247DC324&playnext=1&playnext_from=PL&index=20
Lecture - 22 PERL - Part II
https://www.youtube.com/watch?v=ELp9ytLjupE&feature=PlayList&p=04D5787E247DC324&index=21
Lecture - 23 PERL - Part III
https://www.youtube.com/watch?v=TNIaPKDu678&feature=PlayList&p=04D5787E247DC324&index=22
Lecture -24 PERL-Part IV
https://www.youtube.com/watch?v=-GMDuG-bVfw&feature=PlayList&p=04D5787E247DC324&index=23
printf<<terminator
this is a paragraph
terminator
@month --> array
$month[1] --> second element, month
@color = ( "red", "green", "blue", "black" )
<--> @color = qw(red green blue black)
#here qw quote word
$color[1] <--> green
@array1=@array2
@allcolors = ("white" @colors "blown")
@xyz=(2..5); <---> @xyz=(2,3,4,5)
@xyz=(1 @xyz);
@xyz=(@xyz,6);
-- -----------------------------------
($x, $y, $z)=(10, 20, 30);
($x, $y) = ($y, $x);
($a, @col)=("red", "green", "blue")
($first, @val, $last)=(1,2,3,4) <--> $last will be undefined
-- ---------------------------------
@list=(1,2,3,4);
$first=$list[0];
$list[1]++; ---> # array becomes (1. 3. 3. 4)
$x=$list[5]; $x gets the valuw undef
$list[2]="Go"; #array becomes (1,2,"Go",4)
-- -----------------------------------
$#value --> the index of the last element of the array,
total number minus one
$#value=-1; --> en empty rray has value of -1
-- ---------------------------------
shift and unshift
$first=shift @array;
unshift(@color, "white") --> replace the first element of the array
-- ---------------------------------
pop and push
$first=pop @color --> get the last element of the array
push(@color, "white") --> replace the last element of an array
-- --------------------------------------------------------------
@array2 = reverse @array1;
@array2 = sort @array1;
@array2 = sort ($a <=> $b) @array1; # sort numerically
@middle=splice(@colors,1,2); # remove start from second arguments
for 3rd argument of elements
-- ---------------------------------------------------------------
split --> string, delimiter --> array
--> @array= split / /, $_
join --> $new = join ' ', $x1, $x2, $x3;
$sep=';';
$new = join $sep, $x1, $x2, $x3;
-- ---------------------------------------------------------------
print @colors; --> print without space
print "@colors"; --> print with space
-- --------------------------------------------------------------
<STDIN> <STDOUT> <STDERR>
<stdin> # stdin file handler, <stdin> content of the file handler
chop ($name=<stdin>); chop last character
chmop --> only chop the last character if it is a new lines
$. --> line numer
$_ --> content of current operation
$! --> error code/message
$scalar(localtime)
$out="filename";
open XYZ, ">$out" or die "Error in write: $!"
open XYZ, ">>$out" or die "Error in write: $!"
close XYZ;
-- --------------------------------------------------------------
in perl: three things are considered as FALSE
1): The value 0
2): The empty string ("")
3): undef
-- -------------------------------------------------------------
if ($flag == 1 )
if ($name eq "isa" )
number == != > < >= <=
string eq ne gt it ge le
and &&
or ||
not !
-- -------------------------------------------------------------
break out a loop:
last if ( $i > 10); # similar to break
next # similar to continue
-- -------------------------------------------------------------
@ARGV
foreach (@ARGV) {
print "$_\n";
}
-- ------------------------------------------
=~ ==> match
!~ ==> not match
/ / --> if other delimiter is used, then use m eg: (string =~ m[day[ )
-- -------------------------------------------
if ($string =~ /[0123456789]/) ==> only means digital
^ negation --> if ($string =~ /[^aeiou]) { ... ... }
. any single character except newline
\d digit
\w a word character 0-9a-zA-Z
\s space tab
\D not a digit
\W not a word
\S not a space
^ beginning of the string eg: /^\w/ --> string beginning with a word character
$ end of the string eg: /\d$/ --> end with a number
\b anchors to a word boundary eg: /\bGood\b/
*: zero or more
+: one or more
?: zero or one
-- --------------------------------------------------------------
s: subsitution
$new =~ s/pattern_to_match/new_pattern/;
-- -------------------------------------------------------------
/i: ignore
/g: match/substitute all occurrences
-- ------------------------------------------------------------
\1 \2 \3: if still in regular expression
$1 $2 $3: after reguar expression
$&? string matched
$`? string before matching string
$'? string after matching string
$@
-- -------------------------------------------------------------
%hash
http://perldoc.perl.org/functions/map.html
http://www.devshed.com/c/a/Perl/Hash-Mania-With-Perl/1/
# remove or remove from hash
delete $directory{Atul}
# key value hash reversal
%hash2 = reverse %hash1
@all_names = keys %directory;
@all_values = values %direcory;
-- ----------------------------------------------------
subroutine:
1): arguments
@_
$_[0] $_[1] $_[2]
shift @_
-- ---------------------------------------------------
