=-= Mode #lecture +m by Ch4r
Ch4r ok, let's start with some code:
Ch4r #!/usr/bin/perl
Ch4r print "Hello, world!\n";
Ch4r the above is the infamous 'hello world' script
Ch4r it prints the text 'hello, world' to standard output (the screen)
Ch4r the first line is for UNIX systems - it tells the shell where the perl interpreter is located on the system
Ch4r this line will be ignored by Windows though
Ch4r the second line includes a call to the print() function
Ch4r before, we can completely understand that though, we need to understand what a function, aka a subroutine, is
|<-- Moddy has left irc.binaryuniverse.net (Ping timeout: 181 seconds)
Ch4r a function is one or more lines of code that have a specific purpose and are given a name
Ch4r the print() function comes with the perl interpreter, and its purpose is to print text to standard output
Ch4r as we can see here, the text printed to standard output is "Hello, world!\n"
=-= Mode #lecture -m by Ch4r
Ch4r questions so far?
mu-tiger what's "n"?
qwertydawom no, you can keep it up
Ch4r I'll get to that in a minute, mu
mu-tiger k
Ch4r well, ok
=-= Mode #lecture +m by Ch4r
Ch4r the only part of this that isn't obvious is the "\n", heh
Ch4r \n is what is called an escape sequence, and is used to print 'special' characters
Ch4r \n is the newline character
Ch4r there are other 'escape characters', such as \t, which is a tab, and \a, which is a bell
=-= Mode #lecture -m by Ch4r
Ch4r clear?
mu-tiger bell?
Ch4r it makes a small noice
Ch4r noise*
qwertydawom =ding
mu-tiger k
qwertydawom :)
Ch4r yeah
Ch4r :P
Ozzy cool
Ch4r ok, moving on
=-= Mode #lecture +m by Ch4r
Ch4r *looks through notes*
Ch4r oh, and one more thing regarding the code
Ch4r you can see that the line that prints a string, or text, to standard output ends with a semicolon;
Ch4r all statements in Perl should be terminated with a semicolon
Ch4r right, moving on to the next code sample
Ch4r Code:
Ch4r #!/usr/bin/env perl
Ch4r # The infamous 'hello, world' script...
Ch4r print "Hello".", wor"; # print part of the phrase
Ch4r print("ld","!\n"); # print the other part
Ch4r this is a slightly more complex version of the previous script, ,but it does *exactly* the same thing
Ch4r this is a slightly more complex version of the previous script, ,but it does *exactly* the same thing
Ch4r the first line is still the location of the Perl interpreter on *nix systems. The difference is that using #!/usr/bin/env perl instead of #usr/bin/perl is more portable - it tells the system to find the perl interpreter, wherever it is within the path.
Ch4r whereas using the line #!/usr/bin/perl states to use the Perl interpreter within the dir /usr/bin
=-= Mode #lecture -m by Ch4r
Ch4r Qs?
qwertydawom yeah
qwertydawom yeah
Ch4r ok..?
qwertydawom to concatenate strings
qwertydawom do we have to use "." or "," ?
Ch4r hm?
Ch4r I'll get to that in a moment ;)
qwertydawom ok :)
Ch4r ok..?
qwertydawom to concatenate strings
qwertydawom do we have to use "." or "," ?
Ch4r hm?
Ch4r I'll get to that in a moment ;)
qwertydawom ok :)
Ch4r right. Anyone else?
Ch4r ok
Ch4r moving on
-->| Peradox (~Peradox@adsl-67-124-248-105.dsl.snfc21.pacbell.net) has joined #lecture
=-= Mode #lecture +m by Ch4r
Ch4r hey Peradox
Ch4r anyway, moving on :P
Ch4r the second line of the code is what is referred to as a comment. Comments are like a coder's "notes-to-self", and are completely ignored by the perl interpreter
Ch4r in Perl, lines are made comments by beginning the line with a #. The space from the # until the end of the line is ignored by perl
Ch4r the third line of the code includes a call to print()
Ch4r this time however, tell it to print:
Ch4r "hello".", wor"
Ch4r so you might be wondering - wtf is that dot?
Ch4r the dot is the concatenation operator. It's used to join two strings together in perl
Ch4r so in this example, "Hello" and ", wor" are joined together resulting in the string "Hello, wor"
Ch4r the next line is *another* call to print() as you can see. This time print is told to print ("ld","!\n")
Ch4r first off, what's up with the parentheses?
Ch4r the answer is that the argument(s) passed to print, the string(s) you want print to, erm, print, can be enclosed within parentheses
Ch4r then parentheses are, though, completely optional
Ch4r next question -
Ch4r what's up with the comma
Ch4r it turns out that we can actually tell print to print more than one string. If we want print to print two strings, we pass the to the print function separated by a comma
Ch4r in this case, the two strings are "ld" and "!\n", which are the characters 'ld!' and a newline
=-= Mode #lecture -m by Ch4r
Ch4r questions?
mu-tiger lemme scroll =/
Ch4r am I going too fast? :\
Peradox no
Peradox fine
Ch4r ok
mu-tiger what's "ld?"
qwertydawom worLD ;)
mu-tiger =/
Ch4r "ld" is one of the strings to be printed by print()
mu-tiger this is over my fucking head
Peradox lol dude, it's just stdio
Ch4r what else don't you understand? I can probably explain it more thoroughly
Ch4r Peradox, you're a bit more experienced than some of the other people in here ;)
mu-tiger i mean, maybe i better stick to the first way
Peradox oh, sorry
mu-tiger i don't understand what concentrators are and why if
Ch4r ok,
mu-tiger it's more complicated you don't just do it the easier way, or i guess me, at least to learn
Ch4r concatenating is simply joining two strings together into one string
mu-tiger ok
mu-tiger but why print "hello world" in all those pieces?
qwertydawom lol
Ch4r haha, no reason
qwertydawom that's an example
mu-tiger instead of a nice smooth "hello world?"
Ch4r it's just to illustrate some new concepts of perl
mu-tiger so i shouldn't worry about it for now?
mu-tiger for myself?
Ch4r right
mu-tiger ok
mu-tiger sorry
Ch4r lol
Ch4r np
Ch4r any more questions?
Ch4r well, ok
=-= Mode #lecture +m by Ch4r
Ch4r next up is the concept of variables
Ch4r first, some more code though:
Ch4r #!/usr/bin/env perl
Ch4r $variable = "hi";
Ch4r print $variable, " there\n";
Ch4r the first line should be pretty clear by now
-->| yosyp_ (~yosyp@pool-70-108-80-79.res.east.verizon.net) has joined #lecture
Ch4r the second requires some explanation though... simply put, we assign the variable '$variable' the value "hi"
Ch4r so wtf are variables, you're probably wondering.
Ch4r Variables allow us to represent strings, numbers, or other pieces of data with one single word.
Ch4r in this case, the name $variable now holds the value "hi"
Ch4r we can now use the name $variable anywhere we could use the word "hi". For instance:
Ch4r print $variable;
Ch4r would print "hi" to standard output
Ch4r $variable . " more text";
Ch4r that would result in the string "hi more text"
Ch4r because we're simply concatenation $variable, or "hi", with " more text"
-->| CreepyNodque (~nova@L0153P03.dipool.highway.telekom.at) has joined #lecture
Ch4r getting back to the code, the next line prints "hi there\n"
Ch4r why?
Ch4r because we're passing two arguments, or strings to be printed, to print()
Ch4r the first is $variable, which contains the text "hi"
Ch4r the second is " there\n", which contains 'there' and a newline. The result is that the two strings are printed in the order they appear, and "hi there" + a newline is printed to standard output
=-= Mode #lecture -m by Ch4r
Ch4r questions?
Ch4r oh, and hey creepy, hey yosyp ;)
mu-tiger nope :D
yosyp_ hi Ch4r
yosyp_ nice lexture
Ch4r thanks
Ch4r any more questions?
yosyp_ are you gonna go on further/
Ch4r yeah
Peradox lol
yosyp_ go ahead
Ch4r ok
Known Networks ChatZilla error Connected Networks <none>
URL irc://foo/bar Not Connected Lag <unknown>
URL irc://irc.binaryuniverse.net/lecture Mode +nt Users 8, 0@, 0%, 0+
Topic BU/HL Lectures || Next lecture is TODAY at 10 PM GMT +0
URL irc://foo/bar Connected via <none>
<none>
<none>
URL irc://foo/bar Connected to <none>
<none>
File Progress <unknown>
#lecture
Ch4r concatenating is simply joining two strings together into one string
mu-tiger ok
mu-tiger but why print "hello world" in all those pieces?
qwertydawom lol
Ch4r haha, no reason
qwertydawom that's an example
mu-tiger instead of a nice smooth "hello world?"
Ch4r it's just to illustrate some new concepts of perl
mu-tiger so i shouldn't worry about it for now?
mu-tiger for myself?
Ch4r right
mu-tiger ok
mu-tiger sorry
Ch4r lol
Ch4r np
Ch4r any more questions?
Ch4r well, ok
=-= Mode #lecture +m by Ch4r
Ch4r next up is the concept of variables
Ch4r first, some more code though:
Ch4r #!/usr/bin/env perl
Ch4r $variable = "hi";
Ch4r print $variable, " there\n";
Ch4r the first line should be pretty clear by now
-->| yosyp_ (~yosyp@pool-70-108-80-79.res.east.verizon.net) has joined #lecture
Ch4r the second requires some explanation though... simply put, we assign the variable '$variable' the value "hi"
Ch4r so wtf are variables, you're probably wondering.
Ch4r Variables allow us to represent strings, numbers, or other pieces of data with one single word.
Ch4r in this case, the name $variable now holds the value "hi"
Ch4r we can now use the name $variable anywhere we could use the word "hi". For instance:
Ch4r print $variable;
Ch4r would print "hi" to standard output
Ch4r $variable . " more text";
Ch4r that would result in the string "hi more text"
Ch4r because we're simply concatenation $variable, or "hi", with " more text"
-->| CreepyNodque (~nova@L0153P03.dipool.highway.telekom.at) has joined #lecture
Ch4r getting back to the code, the next line prints "hi there\n"
Ch4r why?
Ch4r because we're passing two arguments, or strings to be printed, to print()
Ch4r the first is $variable, which contains the text "hi"
Ch4r the second is " there\n", which contains 'there' and a newline. The result is that the two strings are printed in the order they appear, and "hi there" + a newline is printed to standard output
=-= Mode #lecture -m by Ch4r
Ch4r questions?
Ch4r oh, and hey creepy, hey yosyp ;)
mu-tiger nope :D
yosyp_ hi Ch4r
yosyp_ nice lexture
Ch4r thanks
Ch4r any more questions?
yosyp_ are you gonna go on further/
Ch4r yeah
Peradox lol
yosyp_ go ahead
Ch4r ok
=-= Mode #lecture +m by Ch4r
=-= Mode #lecture -m by Ch4r
Ch4r yes, dlab?
dlab why are you using env for perl?
Peradox to make the code portable
Ch4r as I said, it's more portable than using a specific path to use #/usr/bin/env perl
Peradox he uses a nice little unbix trick
dlab aah
mu-tiger :)
Ch4r because then it finds Perl whertever it is within the path
Ch4r any more questions?
dlab but then /bin/sh -c 'perl' would work as well
dlab although, env is a lot less overhead
mu-tiger what's "sh"?
Peradox a shell
dlab mu-tiger: Its a shell
mu-tiger thought so
mu-tiger ty
dlab that's off topic
dlab sorry, continue Ch4r
Ch4r dlab, well, I'll have to look into using /bin/sh -c 'perl' :P
Ch4r ok, thanks. Np
=-= Mode #lecture +m by Ch4r
Ch4r we can even assign a variable to a variable.
Ch4r For instance:
Ch4r $anothervar = $variable;
Ch4r $anothervar sitll holds the value "hi"
Ch4r now, moving on to receiving input
Ch4r take a look at this code:
Ch4r #!/usr/bin/env perl
Ch4r print "Enter a string: ";
Ch4r chomp($a = <STDIN>);
Ch4r print "\"$a\" <-- that's what you said\n";
Ch4r the first line shoudl be familiar by now
Ch4r the second line should too. It just prints "Enter a string " to standard output
Ch4r the third line is what's new
Ch4r before we get into what chomp() is, let's analyze $a = <STDIN>
Ch4r <STDIN> represents standard input. Knowing this, we can tell that the variable $a is assigned the value <STDIN>, which is actually whatever the user enters into standard input
Ch4r chomp() is the second function I'm going to tell you about today
Ch4r it simply removes the newline from the end of a string (if there is one)
Ch4r the reason we need to do this is because the input is terminated with a newline, and we might not necessarily want that newline later on. For instance, it could result in unpredictable or unwanted results when we use concatenation
Ch4r the last line, print "\"a\" <-- that's what you said\n"; prints whatever the user entered and then "<-- that's what you said"
Ch4r "\"$a\"*
Ch4r not "\"a\"
Ch4r fucking typo
Ch4r erm
Ch4r anyway
Ch4r so you're probably wondering -what's with the \"?
Ch4r well, we need a way to represent a " character in a string contained within " " without terminating the string too early
Ch4r \" is used to represent " within a double-quoted string
Ch4r we could've just used single-quotes, that probably would have been better and easier, but this looks cooler and allows me to introduce more info in my lecture.
=-= Mode #lecture -m by Ch4r
Ch4r questions?
Peradox i'm not sure if everyone is familiar with procedural programming, so laet me make this clear: chomp($a = <STDIN>); is the same as $a = <STDIN>; chomp($a);
mu-tiger \'==<whatever> in double quotes?
Peradox \ is the escape character
Ch4r mu-tiger, hmm?
mu-tiger the what to achieve double quotes?
Peradox it's used for non printable ASCII characters
Peradox and double quotes so you do not confuse the interpreter
mu-tiger ok
Ch4r ok, now you lost me... :P
dlab in perl, double quotes mean to interpret the line. If a character is preceded with a backslash, then it is interpreted by perl
mu-tiger :D
mu-tiger gotcha
mu-tiger ty xD
Ch4r alright..
dlab like \n gets replaced with a newline, \r gets replaced with a carriage-return
mu-tiger yeah
dlab \0600 gets replaced with the octal value of 600 :/
dlab etc..
mu-tiger :|
Peradox heh
mu-tiger go on charlie
Ch4r ok
Ch4r lol
Peradox wait till you get to 0x32
mu-tiger hush
mu-tiger :(
=-= Mode #lecture +m by Ch4r
Ch4r ok. The last Q and A session (for want of a better term) brings up another topic I haven't introduced yet - single quotes vs. double quotes
Ch4r there is one very important difference between single and double quotes, and that is:
Ch4r when you double-quote a string, any variables in the string are replaced with their values. For instance, print "$a" prints whatever $a contains. When you single-quote a string, however, all characters are interpreted literally. This means that print '$a' prints the text $a and NOT the value $a contains. Similarly, print '\n' does NOT print a newline; it prints the two characters \ and n
|<-- Peradox has left irc.binaryuniverse.net (Client Quit)
Ch4r bye pera
Ch4r ok, next
Ch4r check out this code:
Ch4r #!/usr/bin/env perl
Ch4r $a = 4 + 8;
Ch4r $b = $a * 2;
Ch4r $c = $b / $a;
Ch4r $d = $c * $c * $c % 3;
Ch4r print '$d: ', "$d\n";
Ch4r $a = 10 - 3 * 7;
Ch4r $b = (10 - 3) * 7;
Ch4r print "\$a = $a | \$b = $b\n";
Ch4r by this time the first line should seem like an old friend (Btw, the first line's called the 'shebang' or 'hash bang' line)
-->| Peradox (~Peradox@adsl-67-124-248-105.dsl.snfc21.pacbell.net) has joined #lecture
Ch4r the second line $a = 4 + 8; assignes $a the value of 12, because 12 is, afterall, 4 + 8
Ch4r the third line, $b = $a * 2; assigns $b the value 24. Why? Because the * operator multiplies its operands together and returns the result. In this case, 12 is multipliued by 2, which equals 24.
Ch4r the next line, $c = $b / $a; divides $b by $a and then assigns the result to $c. In this case, 24 divided by 12 equals 2, so $c = 2;
Ch4r the next line multiples 2 times 2 times 2, which equals 8, divides it by 3 and assigns the remainder, 2, to $d
Ch4r then, the following is printed. '$d: ',"$d\n"; this prints the characters '$d: ' to standard output and then the value that $d contains along with a newline
=-= Mode #lecture -m by Ch4r
Ch4r questions so far?
mu-tiger nope :)
Ch4r ok, cool. Anyone else
Ch4r ?*
dlab hmm
Ozzy no, but i g2g. Looking forward to the log
Ch4r laters Ozzy
mu-tiger bye ox
Ozzy bye!
Ch4r dlab, ...?
mu-tiger oz*
|<-- Ozzy has left irc.binaryuniverse.net ("Toodaloo")
dlab maybe you should introduce the perl order of precidence
Ch4r yeah, that's next
mu-tiger :)
Ch4r as you would see if you looked at the code :P
dlab ok :)
Ch4r ok, moving on then
=-= Mode #lecture +m by Ch4r
Ch4r order of precendence determines which part of a mathematical expression in Perl is evaluated first. Take the next line:
Ch4r $a = 10 - 3 * 7; Multiplication and division are evaluated before addition and subtraction, so 3 * 7 is evaluated first, which equals 21. Then the subtraction is evaluated, so 21 is subtracted from 10 and the result is assigned to $a.
Ch4r But what if we wanted the subtraction to be evaluated version, so that first 3 was subtracted from 10 and then the result was multipled by 7?
Ch4r well, it actually isn't very hard. We simply place parentheses around the part we want evaluated first, which is 10 - 3. so (10 - 3) * 7 is the same as 7 * 7
Ch4r because first 3 is subtracted from 10 and then the result is multiplied by 7
Ch4r and then the result is printed
=-= Mode #lecture -m by Ch4r
Ch4r questions?
mu-tiger just like simple algebra
mu-tiger no
Ch4r yep
Ch4r ok
Ch4r no more?
=-= Mode #lecture +m by Ch4r
=-= Mode #lecture -m by Ch4r
Ch4r err
Ch4r I think that's it :P
dlab haha
Ch4r no
qwertydawom what about modulo?
Ch4r it isn't
Ch4r hold on
dlab there are things like quotes and commas in there as well
dlab .. and modulo
Ch4r I already described that, didn't I?
Ch4r yeah
Ch4r scroll up ;)
dlab like a comma has the lowest precidence, etc..
mu-tiger char
mu-tiger restate it for me?
Ch4r mu-tiger, yes?
Ch4r #!/usr/bin/env perl
Ch4r $a = 4 + 8;
Ch4r $b = $a * 2;
Ch4r $c = $b / $a;
Ch4r $d = $c * $c * $c % 3;
Ch4r print '$d: ', "$d\n";
Ch4r $a = 10 - 3 * 7;
Ch4r $b = (10 - 3) * 7;
mu-tiger oh yeah
Ch4r print "\$a = $a | \$b = $b\n";
mu-tiger sorry
Ch4r whoops
Ch4r shit
Ch4r sorry
Ch4r didn't mean to paste the whole thing
Ch4r hm?
mu-tiger no nothing
mu-tiger my bad
mu-tiger ty
Ch4r ok
Ch4r np
Ch4r well, let's move on to conditionals then?
Peradox w00t
qwertydawom you haven't said if % was to be evaluated first
dlab modulo should have the same precidence as division/multiplcation, no?
Peradox yes
Ch4r yeah
qwertydawom ok
Ch4r sorry
Ch4r right, done?
dlab .. yeah
Ch4r well, with questions i mean
Peradox yup
mu-tiger yes
Ch4r ok
=-= Mode #lecture +m by Ch4r
Ch4r here's some more code for you:
Ch4r #!/usr/bin/env perl
Ch4r if (8 > 4) {
Ch4r print "Eight is greater than four!\n";
Ch4r }
Ch4r if (5 < 6 && 7 <= 3) {
Ch4r print "Condition was true.\n";
Ch4r }
Ch4r else {
Ch4r print "Condition was false - else block executed.\n";
Ch4r }
Ch4r this code introduces some new concepts
Ch4r starting at the second line
-->| chedder (1000@S01060000e88e954d.vc.shawcable.net) has joined #lecture
Ch4r lines 2 through 4 contain an if conditional statement
Ch4r so how do we use the if?
Ch4r if takes a condition that is specified between parentheses and checks whether or not it's true. If it is, the code between the curly braces {} is executed (aka, the block of the statement)
Ch4r in this case, if checks whether 8 > 4, whether eight is greater than four. It is, so the print statement between the braces, print "Either is grater than four!\n"; is executed
=-= Mode #lecture -m by Ch4r
Ch4r questions?
dlab yeah
Ch4r ok...?
dlab what about the precidence of boolean operators?
Peradox explain about how expression evaluate
mu-tiger mu-tiger like where he has the "}" is that written on a new line like he just did it?
Peradox if($a)
Peradox for example
Ch4r Peradox, what?
dlab well.. 0 is usually false, and nonzero is true in C
Ch4r yeah
Ch4r oh, that's what you mean? :P
dlab perl supports true booleans though, so..
dlab not sure
Peradox well
Ch4r mu-tiger, what were you saying?
dlab prolly eveluates the same
mu-tiger i thought this was a beginner lecture :|
Peradox you need to show that you can evlaute
dlab evaluates*
Peradox 1 && 0
Ch4r ok, one person at a time please
Peradox and ! || 0
Peradox and so on
dlab yeah
Ch4r I'll get to ||, 7&, etc in a min
Ch4r please don't get ahead of me :)
dlab haha
Peradox k
dlab alright
qwertydawom :)
mu-tiger can i have like
mu-tiger 2 minutes to go do soemthing and try to work this out a sec, too?
mu-tiger and here's what i asked
mu-tiger mu-tiger like where he has the "}" is that written on a new line like he just did it?
Ch4r what exactly are you trying to ask? :/
qwertydawom it's a syntax..
Ch4r the } doesn't necessarily have to be written on a line by itself
Ch4r we could've put it on the same line as the print statement
chedder damn i wish i could be a ninja
chedder damn i wish i could be a ninja
qwertydawom if stuff { blib } else {bla}
mu-tiger when you were showing us Ch4r if (8 > 4) {
mu-tiger Ch4r print "Eight is greater than four!\n";
mu-tiger Ch4r }
dlab ... mu needs another client
mu-tiger that last bracket
dlab anyway..
mu-tiger is on another line?
mu-tiger just like that?
chedder the last bracket dosent matter
dlab doesn't matter if it is
Ch4r it doesn't have to be on another line
chedder it dosent matter mu
chedder it has to be there
mu-tiger ok
chedder but what line its on
mu-tiger brb
Ch4r chedder, it doesn't actually have to be there in this instance ;)
dlab actually, you don't even need the brackets since Ch4r executed a single statement
Ch4r I know
chedder well, it techniqly dosent have to be there anyways
chedder :P
dlab perl is a free-form language
Ch4r mu-tiger, tell me when you're back. we'll wait for you
chedder licks dlab
chedder you back now?
dlab you can have the bracket 6 lines down if you wish
chedder im back on slackware, for some reason
chedder lol
dlab chedder: No
dlab still in oregon
Ch4r please don't go off topic, ched
chedder :(
chedder oh
chedder sorry Ch4r
Ch4r do that in #hackerlounge or #binaryuniverse
Ch4r np
mu-tiger k
Ch4r ok, moving on again
=-= Mode #lecture +m by Ch4r
Ch4r mu-tiger mu-tiger like where he has the "}" is that written on a new line like he just did it?
Ch4r wtf
Ch4r no
mu-tiger lol
=== #lecture The channel demigods have stolen your voice
Ch4r hold on, I'm going to paste the code again
Ch4r #!/usr/bin/env perl
Ch4r if (8 > 4) {
Ch4r print "Eight is greater than four!\n";
Ch4r }
Ch4r if (5 < 6 && 7 <= 3) {
Ch4r print "Condition was true.\n";
Ch4r }
Ch4r else {
Ch4r print "Condition was false - else block executed.\n";
Ch4r }
Ch4r right.
Ch4r so, we aren't limited to checking whether one number is greater than the other with if statements
Ch4r the > (greater than) operator is only one of many we can use
Ch4r some more are:
Ch4r < - less than
Ch4r > - greater than
Ch4r <= - less than or equal to
Ch4r == - equal to
Ch4r >= - greater than or equal to
Ch4r != - not equal to
Ch4r eq - equal to FOR STRINGS
Ch4r ne - not equal to FOR STRINGS
Ch4r && - and
Ch4r || - or
Ch4r for instance,
Ch4r if (5 != 4) evaluates to be true
Ch4r if ( 5 <= 2) does not
Ch4r the last two operators on that list, && and || require a further explanation though
Ch4r it turns out that we can specify more than one condition for an if statement
Ch4r for instance, the second if statement in our code reads:
Ch4r Ch4r if (5 < 6 && 7 <= 3) {
Ch4r Ch4r print "Condition was true.\n";
Ch4r Ch4r }
Ch4r for the expression to evaluate to be true and for the print "Condition was true.\n" to be executed, both of the conditions 5 < 6 and 7 <= 3 must be true
Ch4r the && operator simply means that both conditions specified must be true for the expression as a whole to be true
Ch4r we can use it with more than two expressions though. For example:
Ch4r if (5 != 7 && 2 <= 2 && 99 > 7 && 2 == 2) { ... }
Ch4r the above condition will only be true if 5 is not 7 and 2 is less than or equal to 2 and 99 is greater than 7 and 2 is 2.
=-= Mode #lecture -m by Ch4r
Ch4r questions?
dlab what about boolean OR?
Ch4r yeah, I'll get to that
dlab or is that next? >_>
Ch4r yes
dlab my bad
Ch4r lol, np
dlab shuts up
Ch4r haha
mu-tiger wait a sec charlie
Ch4r ok
chedder pokes #lecture
Ch4r gives chedder his final warning about going off topic and then pokes #lecture.
mu-tiger ok go on
mu-tiger sorry
Ch4r ok, np
=-= Mode #lecture +m by Ch4r
Ch4r ok, next up, logical OR.
Ch4r locgical or is similar to logical and, &&, which I just introduced. The main difference is that if either of its operands is true, the statement as a whole is true. Eg:
Ch4r if (5 > 3 || 9 < 3) { ... }
Ch4r even though nine is certainly not less than three, the statement is still true as a whole. Why? Because 5 is greater than three, and if either of the operands (statements it is used with) is true, the expression as a whole is true.
Ch4r logical ORs and logical ANDs can be used in a single expression as well. For instance:
Ch4r if (5 < 7 || 6 == 6 && 2 > 3) { ... }
Ch4r however, the question of precedence arises once more
Ch4r to acheive the desired results, you may need to enclose part of the expression within parentheses to make sure it's evaluated first.
=-= Mode #lecture -m by Ch4r
Ch4r questions?
dlab what about conditionals? :)
mu-tiger :|
Ch4r dlab, hm?
Ch4r mu-tiger, hmm?
dlab $meh = ($poo == 1) ? 1 : 2;
Ch4r oh, and one more note. Do NOT confuse bitwise and logical and/or operators with one another. They're a bit different.
mu-tiger bitwis?
dlab Ch4r: Indeed. :)
mu-tiger wtf?
mu-tiger cries
Ch4r dlab, oh. I'm not planning on including the ? : notation
Ch4r mu-tiger, what's wrong?
dlab mu-tiger: That will prolly come later
mu-tiger nothing cept i'm so lost
mu-tiger i'll try to sort it all later
Ch4r well
Ch4r now's the time for questions
lecture DLAB!
[INFO] No such nick/channel
Ch4r don't be afraid to ask, even if it sounds stupid
mu-tiger well it's just i'm vague on a lot
mu-tiger i'll have to look at it in parts later and ask
mu-tiger go on, pls
Ch4r ok
=-= Mode #lecture +m by Ch4r
Ch4r pardon me, but I'm going to need to paste the code again ^_^
Ch4r #!/usr/bin/env perl
Ch4r if (8 > 4) {
Ch4r print "Eight is greater than four!\n";
Ch4r }
Ch4r if (5 < 6 && 7 <= 3) {
Ch4r print "Condition was true.\n";
Ch4r }
Ch4r else {
Ch4r print "Condition was false - else block executed.\n";
Ch4r }
Ch4r ok, next up is the else { ... } statement.
Ch4r else statements are used along with if statements. If the condition specified in the parentheses of the if(){} statement is true, the body of the if statement is executed. We already know this. However, what if it's false? Well, if the if statement is alone, we just go on to the next code. If however, the if statement contains a corresponding else block, the else block is executed.
Ch4r for instance, take a look at the following code:
Ch4r if (5 == 6) {
Ch4r # do something
Ch4r }
Ch4r else {
Ch4r # do something else
Ch4r }
|<-- qwertydawom has left irc.binaryuniverse.net (Client Quit)
Ch4r well, it turns out that 5 does NOT equal six, so the if statement is not executed. However, the if statement has an else statement right after it, so the else statement is executed. in this case, the else statement is simply a comment, # do something else, though.
=-= Mode #lecture -m by Ch4r
Ch4r questions?
Ch4r ok then
Ch4r </lecture>
dlab ?
dlab end?
Ch4r yeah
dlab what about elif?
mu-tiger what's an example of the "else?
mu-tiger "
mu-tiger dlab it ws a beginner lecture!!!
Ch4r mu-tiger, I thought I just gave an example. But here's another :P
mu-tiger jumps up and down
Ch4r haha
dlab if($input eq "hi") { print "Hello"; } else { print "Bye"; }
Ch4r yeah
Ch4r :)
mu-tiger good
mu-tiger awesome
mu-tiger you're redeemed, dlab
Ch4r haha
mu-tiger hehe
dlab o_O
mu-tiger ty
Ch4r dlab, I'll introduce elif next lecture maybe
mu-tiger well you confused me
dlab alright
mu-tiger asking all that stuff about booleans and stuff
dlab because its an important conditional
mu-tiger well i'm new and dumb
Ch4r important?
dlab esp. since switch() only accepts ints :/
Ch4r yeah
Ch4r true
Peradox now how about loops??
Ch4r next lecture
Peradox ahh