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string.sub

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string.sub

DragonAwper
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13.03.11 03:05:35 pm

My questions are:

What string.sub exactly do?

What string.len do?

What tonumber do?

What loadstring do?

I think loadstring is to load a variable in run-time

=========================
Look this: It's a kick Script

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function saykick(id, txt)
     if(string.sub(txt,1,5)=="!kick") then
          parse("kick "..(tonumber(string.sub(txt,7,string.len(txt)))).." Kicked!")
     end
end

In this case why it's used?

(txt,1,5)=="!kick")

I don't understand why is: txt,1,5
I think is to return 5 letter form the text

Here too

(txt,7,string.len(txt))
I think is to return 7 letter form the text

Am I correct?

I'm new in lua

And i don't know what these things exactly do.

Help-me

edited 2×, last 13.03.11 03:36:02 pm

Re: string.sub

Banaan
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13.03.11 03:47:34 pm

Ever considered taking a look at the Lua manual, PIL, other Lua tuts? Those are like the easiest basic functions in Lua. Google is your friend. http://lmgtfy.com/?q=lua+string.sub

Lua-users.org wiki has written

string.sub(s, i [, j])
s:sub(i [,j])

Return a substring of the string passed. The substring starts at i. If the third argument j is not given, the substring will end at the end of the string. If the third argument is given, the substring ends at and includes j.

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> = string.sub("Hello Lua user", 7)      -- from character 7 until the end
    Lua user
    > = string.sub("Hello Lua user", 7, 9)   -- from character 7 until and including 9
    Lua
    > = string.sub("Hello Lua user", -8)     -- 8 from the end until the end
    Lua user
    > = string.sub("Hello Lua user", -8, 9)  -- 8 from the end until 9 from the start
    Lua
    > = string.sub("Hello Lua user", -8, -6) -- 8 from the end until 6 from the end
    Lua

Googling the rest ain't that hard...

http://lmgtfy.com/?q=lua+string.len
http://lmgtfy.com/?q=lua+tonumber
http://lmgtfy.com/?q=lua+loadlib

Re: string.sub

DannyDeth
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13.03.11 04:06:35 pm

string.sub = is a function called 'sub' in the wtring module. 'sub' is short for subsection, and that is what it does. It takes the subsection between the two last numbers and the variable supplied ( txt in banaan's case ).

Re: string.sub

DragonAwper
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13.03.11 04:12:26 pm

Good! It's help-me
And i'm not Wrong, Uhuw!

My area of programming is Visual Basic and Delphi
I'm really good in C++ and C#
But in Lua I am a failure

Thanks Banaan and DennyDeath

Re: string.sub

Yasday
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13.03.11 04:15:12 pm

Lua is much easier than c++/c#..

Re: string.sub

DannyDeth
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13.03.11 04:21:09 pm

Yasday has written

Lua is much easier than c++/c#..

Exactly. I double your statement.

Example of C/C++"

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#include <stdio.h>
int main(void){
	printf("Hello World!\n");
	return 0;
}

Example of Lua:

print("Hello World!")

It even cut two extra chars off the last bit of "Hello World!\n" ( well, it would only print one character [ newline ], but yeah, in the code it was to chars

)

And don't make me go into memory management

Re: string.sub

DragonAwper
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13.03.11 04:27:20 pm

Now in Visual Basic

Sub Print()
text="Hello World!"
debug.print text
End Sub

Result: Hello World!

Re: string.sub

DannyDeth
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13.03.11 04:40:53 pm

Visual BASIC is a disgrace of a language. Never show code like that in this forum again! *Bans VB code for ever*

Re: string.sub

DragonAwper
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13.03.11 04:45:02 pm

kkkkk, ok.
Lua is cool, and now i know what is string.BláBlá

But tonumber still confused

Now what DragonAwper understand from this code?

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function saykick(id, txt)
     if(string.sub(txt,1,5)=="!kick") then
          parse("kick "..(tonumber(string.sub(txt,7,string.len(txt)))).." Kicked!")
end
end

Line 2 : if 1-5 character == "kick" then
(look theres 5 chars.!) now it's explain why is txt 1,5

Line 3 : Kick the Number that's stay on the 7th space form the text to the text lenght,
And the reason is "Kicked!"

Am I right?

edited 2×, last 13.03.11 04:58:56 pm

Re: string.sub

Flacko
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13.03.11 05:40:31 pm

Yes you are.

The tonumber function is used to convert lua strings representing a number to an actual number.
For example: tonumber("5") returns 5.

You can't perform any arithmetical operations on a string representing a number, like addition, substraction, multiplication, etc, but you can do so if you convert it to a number.

However, in the code you posted here there's no need to use tonumber() because when the kicked player id is converted to a number it is then converted to a string again for concatenation.

If you read the Lua manual you'll see that this is called coercion, Lua converts a number to a string if needed when you're trying to concatenate it to a string. Moreover, Lua also converts a string to a number if you attempt any arithmetical operations on it.
For example: "5"+3 returns 8

Re: string.sub

Danikah
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13.03.11 06:19:37 pm

DragonAwper has written

Now in Visual Basic

Sub Print()
text="Hello World!"
debug.print text
End Sub

Result: Hello World!

Now in GML!

draw_text(x,y,"Hello World!")

But anyway, these answers helped me too alot.

Re: string.sub

DragonAwper
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13.03.11 07:53:59 pm

@Flacko
Great explanation! Now I understand better than before!
Thanks.

@Danikah
Very Good

@Topic
What is the best way to create a kick system?

Number 1

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addhook("say","saykick")
function saykick(id, txt)
     if(string.sub(txt,1,5)=="!kick") then
          parse("kick "..(tonumber(string.sub(txt,7,string.len(txt)))).." Kicked!")
     end
end

Number 2

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function saykick(id, t)
	if t:sub(1,5)=="!kick" then
		kid=tonumber(t:sub(7,8))
		parse("kick "..kid)
	end
end

This Question is very simply, but i want to see your Opinion

Re: string.sub

KimKat
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13.03.11 07:58:34 pm

What if the end is unknown?

So like...

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x = 9 -- and further?
string.sub("Hello Lua user", 7,"..x)

Just wondering how to read after the 7th character...

Re: string.sub

DragonAwper
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13.03.11 08:04:23 pm

Eh, if have 32 players it's possible to kick, look:

7,8;
It's 2 Characters

0 - 9 = 1 char.
10 - 99 = 2 char

About this i have 2 Replies:

Yes I can create a Loop Structure with 1 to 32 but my examples are only "Examples"

Yes I can use the String.Len too but my examples are only "Examples"

Re: string.sub

KimKat
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13.03.11 09:43:04 pm

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addhook("say","on_say")
function on_say(id,txt)
	slay = to.number(text[txt],1,7,8)
	if (txt=="!slay") then
		slay(id)
	end
end

for i = 1, 32 do
	text = string.sub(txt,i,"..string.len[i(s)]..")
	s = string.sub(s, 2)
	return s
end

What would this code do? I tried to understand it. I wanted it to do a check on how long the length it is on "i" lol, and thereafter limit it by just that from 1-32 it shouldn't go further than this... sort of like going through all these and seeing who said what from the say function in order to slay the id given. Maybe it's pathetic, but I really tried to understand this...

Re: string.sub

Banaan
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13.03.11 10:11:13 pm

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local kid = t:match("%d+")
parse("kick " .. kid)

Note that this only works when there's just one id in there, as it will match each number in your string. (so !kick 23 will return 23, but !1 kick 23 will return 1)

Re: string.sub

Flacko
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13.03.11 10:45:55 pm

Ugh, people, better use Lee's string.split() function

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function string.split(text,delimiter)
	local buff = {}
	delimiter = "[^"..(delimiter or " ").."]+"
	for w in string.gmatch(text,delimiter) do
		table.insert(buff,w)
	end
	return buff
end

This way you can easily split a text into tokens and access those words.
Example:

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addhook("say","_say")
function _say(id,txt)
	txt = string.split(txt," ") --Txt is now a table storing it's words
	if txt[1] == "!kick" then --if the first word is kick
		parse("kick "..txt[2]) --We kick the player given in the second word
	end
end

Dealing with all those string.sub, string.len, etc causes me headache.

Re: string.sub

KimKat
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13.03.11 10:58:07 pm

@Flacko: Talking about headaches I had one earlier, lol. If I wanted to kick player 33 it would produce a Lua error that the player don't exist, so is there a way to ignore values over 32 or less than 1 let's say 0 (or even -1) though? is there a way to like "return 1"(ignore) it? as to not produce a Lua error. I like your script Flacko, it seems too be functional. So the second word being a number, would that be counted as is? In example id 2 or id 22 would read as is...

If so this script you did, would be quite epic and useful.

Ignore other values like this perhaps...

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if txt[2]>=33 or txt[2]<=0 then
	return 1
end

Re: string.sub

Danikah
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13.03.11 11:16:46 pm

Er...

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if player(txt[2],exists)
   parse("kick "..txt[2]) --We kick the player given in the second word

Maybe?

Re: string.sub

Flacko
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13.03.11 11:24:13 pm

Yes, would be something like that, but txt[2] is a string, not a number (as the player function espects)
So the right solution that I think you're looking for would be something like this:

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addhook("say","_say")
function _say(id,txt)
	txt = string.split(txt," ") --Txt is now a table storing it's words
	if txt[1] == "!kick" then --if the first word is !kick
		if player(tonumber(txt[2]),"exists") then --and the given id is a player
			parse("kick "..txt[2]) --We kick the player given in the second word
		end
		return 1 --Don't display any text
	end
end