Uvod v Perl ukaze
Perl je programski jezik. Prej zasnovan samo za urejanje besedil, zdaj se uporablja za številne namene, kot je sistemska administracija v Linuxu, razvoj spletnih strani, omrežno programiranje itd. Glavni arhitekt in ustvarjalec Perla je Larry Wall. Izdelana je bila leta 1987 in se še vedno uporablja kot glavni programski jezik. Perl je jezik na visoki ravni. Je tudi tolmačen in dinamičen programski jezik. Zdaj se bomo podrobno naučili Perl ukazov.
Osnovni ukazi Perl
1. Osnovni ukaz Perl za tiskanje v Perlu
#!/usr/bin/perl
# This will print "Hello, World"
print "Hello, world\n";
2. Komentar z eno vrstico v Perlu
#!/usr/bin/perl
# This is a single line comment
print "Hello Perl\n";
3. Komentar z več vrsticami v Perlu
#!/usr/bin/perl
=begin comment
This is a multiline comment.
Line 1
Line 2
Line 3
We can insert
as much lines
as comments
until we code =cut
to end multiline comments
=cut
print "Hello Perl\n";
4. Spremenljivka spremenljivke v Perlu (interpolacija spremenljivk z dvojnim citiranjem)
#!/usr/bin/perl
$a = 10;
print "Variable a = $a\n";
5. Pobežni lik v Perlu
#!/usr/bin/perl
$a = "This is \"Perl\"";
print "$a\n";
print "\$a\n";
6. V Perlu imajo strune različno obnašanje z dvojnimi narekovaji in enojnimi navedki. Medtem ko dvojne navedbe omogočajo interpolacijo, posamezne navedbe ne.
#!/usr/bin/perl
# Interpolation example.
$str = "Hello \nPerl";
print "$str\n";
# Non-interpolation example.
$str = 'Hello \nPerl';
print "$str\n";
7. Zgornja zadeva v ukazu Perl
#!/usr/bin/perl
# Only u will become upper case.
$str = "\uhello perl";
print "$str\n";
# All the letters will become Uppercase.
$str = "\Uhello perl";
print "$str\n";
# A portion of string will become Uppercase.
$str = "hello \Uperl\E";
print "$str\n";
8. Dodelitev skalarne spremenljivke v Perl
#!/usr/bin/perl
$age = 35; # Assigning an integer
$name = "Tony Stark"; # Assigning a string
$pi = 3.14; # Assigning a floating point
print "Age = $age\n";
print "Name = $name\n";
print "Pi = $pi\n";
9. Preproste skalarne operacije v Perlu
#!/usr/bin/perl
$constr = "hi" . "perl";# Concatenates two or more strings.
$add = 40 + 10; # addition of two numbers.
$prod = 4 * 51;# multiplication of two numbers.
$connumstr = $constr . $add;# concatenation of string and number.
print "str = $constr\n";
print "num = $add\n";
print "mul = $prod\n";
print "mix = $connumstr\n";
10. Posebni literali v Perlu
#!/usr/bin/perl
print "Current file name ". __FILENAME__ . "\n";
print "Current Line Number " . __LINENO__ ."\n";
print "Current Package " . __PACKAGENAME__ ."\n";
# here they cannot be interpolated
print "__FILENAME__ __LINENO__ __PACKAGENAME__\n";
Vmesni ukazi Perl
1. Nizi v Perlu
Indeks matrike se začne od 0. Negativni indeks označuje elemente z zadnjega položaja. Spodnji primer.
#!/usr/bin/perl
@weekday = qw/Mon Tue Wed Thu Fri Sat Sun/;
print "$weekday(0)\n";
print "$weekday(1)\n";
print "$weekday(2)\n";
print "$weekday(6)\n";
print "$weekday(-1)\n";
print "$weekday(-6)\n";
2. Niz za elemente v zaporedju
#!/usr/bin/perl
@oneToTen = (1..10);
@fiftyToSeventyfive = (50..75);
@aToZ = (a..z);
print "@oneToTen\n"; # Prints one to ten
print "@fiftyToSeventyfive\n"; # Prints fifty to seventy five
print "@aToZ\n"; # Prints from a to z
3. Dodajanje in odstranjevanje elementov matrike
#!/usr/bin/perl
# creating an array
@expression = ("happy", "sad", "angry");
print "1. \@expression = @expression\n";
# add element to the end of the arraypush(@expression, "jolly");
print "2. \@expression = @expression\n";
# add element to the beginning of the arrayunshift(@expression, "excited");
print "3. \@expression = @expression\n";
# remove element to the last of the array.pop(@expression);
print "4. \@expression = @expression\n";
# remove element from the beginning of the array.shift(@expression);
print "5. \@expression = @expression\n";
4. Prepere v Perlu
Hash je koncept ključnega para. Spodaj je primer za ustvarjanje hash-a.
#!/usr/bin/perl
%data = ('Mohan Singh' => 55, 'Ram Gupta' => 25, 'Bhuvan Kumar' => 31);
@age = values %data;
print "$age(0)\n";
print "$age(1)\n";
print "$age(2)\n";
5. Dodajanje in odstranjevanje osvetlitvenih elementov
#!/usr/bin/perl
%data = ('Mohan Singh' => 55, 'Ram Gupta' => 25, 'Bhuvan Kumar' => 31);
@keys = keys %data;
$size = @keys;
print "a - Hash size: $size\n";
# add an element to the hash;
$data('Imran Khan') = 44;
@keys = keys %data;
$size = @keys;
print "b - Hash size: $size\n";
# delete an element from the hash;
delete $data('Imran Khan');
@keys = keys %data;
$size = @keys;
print "c - Hash size: $size\n";
6. Pogojna izjava v Perlu: če… elsif… drugo
#!/usr/local/bin/perl
$num = 50;
# check condition using if statement
if( $num == 40 ) (
# print the following if true
printf "num has a value which is 20\n";
) elsif( $num == 60 ) (
# else print if the next condition is true
printf "num has a value which is 30\n";
) else (
# if none is true print following
printf "num has a value which is $num\n";
)
7. Pogojna izjava v Perlu: razen… elsif… izjava drugega
#!/usr/local/bin/perl,
$num = 50;
# check condition using unless statement
unless( $num == 25) (
# if condition is false then print the following
printf "num has a value which is not 25\n";
) elsif( $num == 55) (
# if condition is true then print the following
printf "num has a value which is 55";
) else (
# if both the condition is dissatisfied, print the
original value
printf "num has a value which is $num\n";
)
8. Zank v Perlu: medtem ko zanka
#!/usr/local/bin/perl
$i = 1;
# while loop
while( $i < 5 ) (
printf "Value of i: $i\n";
$i = $i + 1;
)
9. Zank v Perlu: Do zanke in za zanko
#!/usr/local/bin/perl
$i = 1;
# until loop
until( $i > 5 ) (
printf "Value of i: $i\n";
$i = $i + 1;
)
# for loop
for ($j = 0; $j < 3; $j++) (
printf "Value of j: $j\n";
)
10. Zanke v Perlu: naredite … medtem ko zanka
#!/usr/local/bin/perl
$i = 10;
# do…while loop
do(
printf "Value of i: $i\n";
$i = $i + 1;
)
while( $i < 20 );
Napredni Perl ukazi
1. Programiranje vtičnic v Perlu: Server
#!/usr/bin/perl -w
# Filename : server.pl
use strict;
use Socket;
# use port 8081 as default
my $port = shift || 8081;
my $protocol = getprotobyname('tcp');
my $server = "localhost"; # Host IP running the
server
# create a socket, make it reusable
socket(SOCKET, PF_INET, SOCK_STREAM,
$protocol)
or die "Can't open socket $!\n";
setsockopt(SOCKET, SOL_SOCKET,
SO_REUSEADDR, 1)
or die "Can't set socket option to SO_REUSEADDR
$!\n";
# bind to a port, then listen
bind( SOCKET, pack_sockaddr_in($port,
inet_aton($server)))
or die "Can't bind to port $port! \n";
listen(SOCKET, 5) or die "listen: $!";
print "SERVER started on port $port\n";
# accepting a connection
my $client_addr;
while ($client_addr = accept(NEW_SOCKET,
SOCKET)) (
# send them a message, close connection
my $name = gethostbyaddr($client_addr,
AF_INET );
print NEW_SOCKET "Smile from the server";
print "Connection recieved from $name\n";
close NEW_SOCKET;
)
2. Programiranje vtičnic v Perlu: odjemalec
!/usr/bin/perl -w
# Filename : client.pl
use strict;
use Socket;
# initialize host and port
my $host = shift || 'localhost';
my $port = shift || 8081;
my $server = "localhost"; # Host IP running the
server
# create the socket, connect to the port
socket(SOCKET, PF_INET, SOCK_STREAM, (getproto
byname('tcp'))(2))
or die "Can't create a socket $!\n";
connect( SOCKET, pack_sockaddr_in($port,
inet_aton($server)))
or die "Can't connect to port $port! \n";
my $line;
while ($line = ) (
print "$line\n";
)close SOCKET or die "close: $!";
3. Povezovanje z bazo podatkov s pomočjo Perl
#!/usr/bin/per
use DBI
use strict;
my $driver = "mysql";
my $database = "DBTEST";
my $dsn = "DBI:$driver:database=$database";
my $userid = "user123";
my $password = "pass123";
my $dbh = DBI->connect($dsn, $userid, $password
) or die $DBI::errstr;
4. CGI programiranje z uporabo Perl
#!/usr/bin/perl
print "Content-type:text/html\r\n\r\n";
print '';
print '';
print 'Hello Perl - CGI Example';
print '';
print '';
print '
Pozdravljeni Perl! To je primer programa CGI
';natisni '';
natisni '';
1;
Nasveti in triki za uporabo ukazov Perl
Perl naj bi bil mešanica vseh jezikov, torej je opremljen z najboljšimi lastnostmi večjih programskih jezikov. Najpomembnejši vidik je obvladovanje osnov in nadaljevanje prakse tega jezika. Nadgradnja in samo izboljšava sta ključ do uspeha.
Zaključek
Zgornji programi so vzorci, ki bodo podjetju pomagali razumeti osnove in nadaljevati s samoizpopolnjevanjem. Temu so rekli grdi programski jezik, v resnici pa ima najrazličnejše funkcije. Priporočljivo je, da sledite temu dokumentu, da sestavite kode in razumete, kaj se dogaja v samem programu.
Priporočeni članki
To je vodnik za Perl ukaze. Tu smo razpravljali o osnovnih, takojšnjih kot tudi naprednih Perlovih ukazih. Če želite izvedeti več, si oglejte tudi naslednji članek.
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