View source for If-Then-Else

__NOTOC__
The If-then-else statement allows you to compare values and execute different parts of a script based on that comparison.

 if (v1 operator v2) { commands1 }
 elseif (v1 operator v2) { commands2 }
 else { commands3 }

If the first statement (line) is [[$true]], commands inside the first brackets are executed. If the first if-statement returns [[$false]], script starts looking for an elseif-statement. An elseif-statement is only triggered if the group's if-statement returned $false before. And at last, if none of the if or elseif statements were triggered, commands in else-statement are executed.

One if structure/group can consist of one main if-statement, after it there can be 0 .. N elseif-statements. There can be only one else, which can be understood as the default statement, if none one before were triggered. There doesn't need to be else-statement though.

Every if statement is handled separatly and none of others affect in another.

 if (A) { ... }
 elseif (B) {
   if (C) { ... }
   elseif (D) { ... }
   elseif (E) { ... }
   else { F }
 }
 elseif (G) { ... }
 else { H }

If structure would be hierarchical represented it would look something like this

 A               If A is true, execute its commands and return
 B               If B is true, 
  \
   C                 check if C, D or E returns true
   D
   E
   F             If none of these got triggered, return F
 G               G is checked only if A or B were not triggered
 H               If none of previous matches, H is returned

== The Operators ==

 [[#==|==]]        equal to
 [[#==|===]]       equal to (case-sensitive)
 [[#!=|!=]]        not equal to
 [[#<|<]]         less than
 [[#>|>]]         larger than
 [[#<=|<=]]        less than or equal to
 [[#>=|>=]]        larger than or equal to
 [[#//|//]]        v2 is a multiple of v1
 [[#\\|\\]]        v2 is not a multiple of v1
 [[#&|&]]         bitwise comparison
 
 [[#isin|isin]]      string v1 is in string v2
 [[#isin|isincs]]    string v1 is in string v2 (case sensitive)
 [[#iswm|iswm]]      wildcard string v1 matches string v2
 [[#iswm|iswmcs]]    wildcard string v1 matches string v2 (case sensitive)
 [[#isnum|isnum]]     number v1 is a number in the range v2 which is in the form n1-n2 (v2 optional)
 [[#isletter|isletter]]  letter v1 is a letter in the list of letters in v2 (v2 optional)
 
 [[#isalnum|isalnum]]   text contains only letters and numbers
 [[#isalpha|isalpha]]   text contains only letters
 [[#islower|islower]]   text contains only lower case letters
 [[#isupper|isupper]]   text contains only upper case letters
 
 [[#ison|ison]]      if v1 is on channel v2
 [[#isop|isop]]      if v1 is an op on channel v2
 [[#ishop|ishop]]     if v1 is a halfop on channel v2
 [[#isvoice|isvoice]]   if v1 has a voice on channel v2
 [[#isreg|isreg]]     if v1 is a normal nick on channel v2
 [[#ischan|ischan]]    if v1 is a channel which you are on.
 [[#isban|isban]]     if v1 is a banned address in the internal ban list for channel v2
 
 [[#isaop|isaop]]     if v1 is a user in your auto-op list for channel v2 (v2 optional)
 [[#isavoice|isavoice]]  if v1 is a user in your auto-voice list for channel v2 (v2 optional)
 [[#isignore|isignore]]  if v1 is a user in your ignore list with the ignore switch v2 (v2 optional)
 [[#isprotect|isprotect]] if v1 is a user in your protect list for channel v2 (v2 optional)
 [[#isnotify|isnotify]]  if v1 is a user in your notify list.

''Note:'' To negate an operator you can prefix it with an exclamation mark (!).

=== == ===
 if (cat == cAt)  ;Returns true since == is case-insensitive.
 if (cat === cAt) ;Returns false since === is case-sensitive.
The above checks that v1 (cat) matches v2 (cAt).

=== != ===
 if (cat != cAt)  ;Returns false since != is case-insensitive and both values v1 and v2 are equal.
 if (cat !=== cAt) ;Returns true since !=== is case-sensitive and both values v1 and v2 are not equal when case is taken in to consideration.
The != and !=== operators are the negates of the == and === operators.

=== < ===
 if (6 < 9) ;Returns true because the numerical value 6 is less than 9.
Checks that v1 (6) has a lower numerical value than v2 (9)

=== > ===
 if (6 > 9) ;Returns false because the numerical value 6 is not greater than 9.
Checks that v1 (6) has a higher numerical value than v2 (9)

=== <= ===
 if (6 <= 9) ;Returns true because the numerical value 6 is less than or equal to 9.
Checks that v1 (6) has a lower or equal numerical value than v2 (9).

=== >= ===
 if (6 >= 9) ;Returns false because the numerical value 6 is not greater than or equal to 9.
Checks that v1 (6) has a greater or equal numerical value than v2 (9).

=== // ===
 if (3 // 9) ;Returns true because 3 is a multiple of 9.
Multiples of 9 are numbers that when devided in to 9 result in an integer.
You are not limited to positive numbers.

=== \\ ===
 if (3 \\ 9) ;Returns false because 3 is a multiple of 9.
\\ is the negate of //

=== & ===
 if (N1 & N2) ; This will compare the bits that are [[$biton|turned on]] in the decimal N1 AND N2 in the same way [[$and]]() would.
As long as N1 and N2 share atleast 1 bit the condition is returned as true.

 if (13 & 11) ;Is true, see the table below for explanation.
 echo -ag $and(13,11) ;returns 9.

If you break down 13 and 11 into their bits as below:
{|class="gallery"
|-
| style="width:100px" | '''''Binary''''' || '''''Value''''' 
|-
| 1101      || 13
|-
| 1011      || 11 
|-
| style="border:1px dotted #2f6fab; color: Black;" | 1001      || style="border:1px dotted #2f6fab; color: Black;" | 9 
|}
 if (11 & 4) ;Is false.
 echo -ag $and(11,4) ;returns 0.
{|class="gallery"
|-
| style="width:100px" | '''''Binary''''' || '''''Value''''' 
|-
| 1011      || 11 
|-
| 0100      || 4
|-
| style="border:1px dotted #2f6fab; color: Black;" | 0000      || style="border:1px dotted #2f6fab; color: Black;" | 0
|}
Above you can see, 13 and 11 both have the first bit AND fourth bit on, so the statement is true. The binary 1001 value has a decimal value of 9.
Also you can see, 11 and 4 do not share any common bits, so the statement is false.

=== isin ===
 if (cat isin [[$1-]])
Matches for "a ''cat''", "''cat''alog", "impli''cat''e " and any string where "cat" '''is in'''.

=== iswm ===
iswm stands for ''is wildcard match''. 

Operators:
 *  0 or more characters
 ?  1 character
 &  1 word (atleast 1 or more non-space characters)


 if (home*away*lost iswm $1-)
This would match anything starting with home and ending in lost, with away being between home and lost.
It would match, "homeawaylost", "home away lost", "home is missed when you are away or lost", etc.


 if (ca?* iswm $1-)
Requires one character after "ca" and allows 0 or more character after it. So it would match for cat, cab, cabin etc.


 if (I & you iswm $1-)
Matches any string that consists of "I + one word + you".
Examples would be, "I love you", "I hate you", "I moo you", it would not however match, "I don't love you" since "don't love" contains a space.

=== isnum ===

 if ($1 isnum)  ;Returns true if $1 is of numeric value
 if ($1 isnum 10-)  ;Returns true if $1 is number higher than 10
 if ($1 isnum 20-30)  ;Returns true if $1 is a number between 20 and 30

The examples above checks $1, to see;

Is it a number?<br />
Is it a number above 10?<br />
Is it a number between 20 and 30?

=== isletter ===

 if ($1 isletter)  ;Returns true if ''$1'' is a letter, any letter
 if ($1 isletter abcdefg)  ;Returns true if ''$1'' is in the string of letters ''abcdefg''
 if ($1 isletter HelloWorld)  ;Returns true if ''$1'' is in the string of letters ''HeloWrd''

* Note that the checking is case-sensitive, the letter ''h'' will not return true if checked against the string ''HelloWorld''.

=== isalnum ===
 if (Dana34 isalnum) ;returns true as ''Dana34'' contains letters and numbers only
 if (Dana_ isalnum) ;returns false as ''_'' is neither letter nor number

Matches whether the string consists of letters and numbers only.

=== isalpha ===
 if (Dana isalpha) ; returns true as ''Dana'' consists of letters only
 if (foo42 isalpha) ; returns false as ''42'' is no letter

Isalpha checks whether the word consists of letters only. It doesn't matter whether there are upper or lower case.

=== islower ===
 if (moo islower) ; returns true as all letters in ''moo'' are lower case.
 if (m0o islower) ; returns true as well as all letters in ''m0o'' are lower case. 
 if (mooO islower) ; retursn false as there is an upper ''O'' in ''mooO''.
'''Note''' that islower checks whether all letters in the string are lower case. There can still be numbers or other characters in the string $1.

=== isupper ===
 if (MOO isupper) ; returns true as ''MOO'' consists of upper case letters only
 if (1234 isupper) ; returns true as all letters in ''1234'' are upper case, as there are none.
'''Note''' that it checks whether all letters in $1 are upper case. There can still be numbers or other characters in $1.

=== ison ===
 if (Dana ison #help.script) ; returns true as ''Dana'' is in the channel #help.script
 if (foo !ison #help.script) ; returns true as ''foo'' is not in #help.script

This checks whether $1 is in the channel $2.

=== isop ===
 if (Dana isop #help.script) ; returns true as ''Dana'' is an operator in #help.script
 if (foo isop #help.script) ; returns false as ''foo'' is no operator in #help.script

Checks whether $1 is an operator in $2.

=== ishop ===
 if (moo ishop #mIRC) ; returns true if ''moo'' is an half operator in #mIRC
'''Note''' that QuakeNet does not support halfops.

=== isvoice ===
 if (Dana isvoice #help.script) ; returns true as ''Dana'' has voice in #help.script.
 if (foobar isvoice #help.script) ; returns false as ''foobar'' has no voice in #help.script.
This checks if $1 has voice in $2 or not.

=== isreg ===
 if (Dana isreg #help.script) ; returns false as Dana is no regular user in #help.script.
 if (foobar isreg #help.script) ; returns true as foobar is a regular user in #help.script.
This checks whether $1 is a regular user (no voice, no half operator, no operator) in $2.

=== ischan ===
 if (#help.script ischan) ; returns true as you are in #help.script.
 if (#foobar ischan) ; returns false as you are no in #foobar.
'''Note''' that it returns true only if you are in this channel.

=== isban ===
 if (idiot!*@* isban #mychan) ; returns $true if ''idiot!*@*'' is in your [[:Category:IBL|Internal Ban List]] for the channel #mychan.
 if ($ial($me) isban $chan) ; returns $true if you are banned on the current channel.
'''Note''' that isban performs two different checks, depending on whether v1 contains wildcards or not:
* if v1 contains wildcards, isban will return $true if v1 is an exact ban in the IBL;
* if v1 does not contain wildcards, isban will return $true if one or more bans match that address.

=== isaop ===
 if (foobar isaop) ; returns true if ''foobar'' is in your autoop list for any channel.
 if (foobar isaop #help.script) ; returns true if ''foobar'' is in your autoop list for #help.script.
To put someone in your autoop-list, take a look at [[Aop|/aop]].

=== isavoice ===
 if (foobar isavoice) ; returns true if ''foobar'' is in your autovoicelist for any channel.
 if (foobar isavoice #help.script) ; returns true if ''foobar'' is your autovoicelist for #help.script.
To put someone in your autovoicelist, take a look at [[Avoice|/avoice]].

=== isignore ===
 if (foobar isignore) ; returns true if ''foobar'' is in your ignore list.
 if (foobar isignore c) ; returns true if ''foobar'' is in your ignore list with switch -c.
To get a more in detail explanation of these switches, take a look at [[Ignore|/ignore]].

=== isprotect ===
 if (foobar isprotect) ; returns true if ''foobar'' is in your protect list.
 if (foobar isprotect #help.script) ; returns true if ''foobar'' is in your protect list for #help.script.
To get more information about protection, see [[Protect|/protect]].

=== isnotify ===
 if (Dana isnotify) ; returns true if Dana is in your notify list.
Take a look at [[Notify|/notify]] to add someone to your notifylist. If someone in your notifylist connects (disconnects), the [[On_notify|On notify event]] ([[On_unotify|On Unotify event]]) is triggered.

== Combining comparisons ==

You can combine comparisons by using the && for AND and || for OR characters.

 [[var]] %c = 5
 if (%c < 6) && (%c > 0)      ; returns true because %c is both, smaller than 6 and greater than 0
 if (%c < 6) || (%c isalpha)  ; returns true because %c is lower than 6.
                              ; note that %c is not alphapetical and returns false, but || matches for 1 .. N true values.
 if (%c < 6) && (%c isalpha)  ; returns false
 if (%c < 6) && (%c !isalpha) ; ! negates the operator, this this returns true

== Notes ==
====''Not all comparations need two parameters''====
 if ($1- isupper)
returns true, if $1- only contain uppercase letters. So ABCD returns true, but even one lowercase letter makes it return false.

====''Use parenthesis right''====
(A) || (B) && (C) <- logical order for this is to check if either one of A or B is true, and C is true, but if you wish to check that B and C must be true, or A is true, you'll need to do (A) || ((B) && (C))

====''This article covers only if-then-else '''string''' operators''====
You '''can't''' use
 if (foo isin test.txt)
To check content of text-files. You can use [[$read]] instead to read the content of a text file and then use the return value returned by that $read.

== Also see ==
* [[$v1]] & [[$v1|$v2]] These identifiers allow you to retrieve the values of the last if condition.

[[Category:Commands]]