[Lua][Questions]Help Needed Regarding Strings And Lists For Use In Api

I very recently got inspired by how binary works. Binary inspired me to make some kind of encryption API. It works that each symbol get a string of 20 symbols. "E" could for example be "aI19SæOj3ASd9hAMs81S" making it very hard to read. The API is supposed to come with two functions:

.encrypt(_string_)
.decrypt(_string_)

I just simply don't know how to: (I did try to find these before posting)

• Make and use a list in Lua.
• Make a list.
• Get the size.
• Refer to a variable in a list.
• Remove a variable in the list.
• Add a variable to the list.
• Combine x amount of strings together to one.
• Separate each symbol in a single string and put them into a list.

Help is very much appreciated.
-Frederikam

well when you need a list you can just use a table, declare a table with

local mytable={}

and add values to it with

mytable["myindex"]="value"

or

mytable.myindex="value"

you can recall values with

print(mytable.myindex)

and it would priint "value".

generally we use tables with consecutive numbers as indexes so

local mytable={}
mytable[1]="first item in list"
mytable[2]="second item in list"

we can also use

table.insert(mytable,"value")

to insert "value" at the lowest empty number

to remove an item from the list use

mytable["myindex"]=nil

or

table.remove(mytable,"myindex")

the table.remove one will also move everything else down a number to fill the gap so for instance

mytable={}
mytable[1]="one"
mytable[2]="two"
mytable[3]="three"
table.remove(mytable,2)
print(mytable[2])

would print "three"

to get the number of items in a list use

print(#mytable)

and it will print the number of items in the table (only those with consecutive indexes starting at 1 will be counted)

if you have a table of strings and want to combine them all into one string use

local totstring=""
for num,sValue in ipairs(mytable) do
  totstring=totstring..sValue
end
print(totstring)

and to separate one string into a table of characters use

local mystring="hello world!"
local tChars={}
for i=1,#mystring do
  table.insert(tChars,string.sub(mystring,i,i))
end

if you have further questions (which I'm sure you will 'cos I suck at explaining things :D/> ) feel free to ask.

Thank you, it is very much appreciated, i just need some explanation on the following:

Is "myIndex" like a name, similar when you use the table.insert() gives the variable a number instead? And please explain how this works:

table.insert(tChars,string.sub(mystring,i,i))

"myIndex" is the place in the table (a number) where you insert something
so if you have randomtable = {}
randomtable[6] = 4
then the 6th slot in the table will have the value 4
while in table.insert() the first argument is the tablename, and the second argument is the value
so table.insert(randomtable, 8) will give the first available slot (in this case the first) the value 8
if you would now do randomtable[1] it will return you 8
if you would do randomtable[6] it will give you 4


table.insert(tChars,string.sub(mystring,i,i))
That will insert the result of string.sub(mystring,i,i) in the first available table slot in the tChars table.
The result of string.sub(mystring,i,i) is of course dependent on i and the string, but i trust you already knew that..
for instance

local mystring="hello world!"
local tChars={}
for i=1,#mystring do
  table.insert(tChars,string.sub(mystring,i,i))
end

That will make i go from 1 to #mystring (the number of characters in the string, in this case 12).
if i arrived at the point at which it is for instance 7, it will do the following
table.insert(tChars,string.sub(mystring,7,7))
so it inserts a value into the first available slot in the tChars table, and that value is the 7th character of mystring, or w

if you would do string.sub(mystring,7,9) it would give you the 7th till the 9th character of mystring, or wor
if you wold do string.sub(mystring,7) it would give you the 7th till the last character of mystring, or world!

Thank you for your explanation, I think that's all i need to make this API.

No problem, and good luck!

I seem to get a problem with this:

test={}
table.insert(test, "gsd")
print(test.1)

In this case I get:

input:3: ')' expected near '.1'

I know test["1"] and test.1 is the same, but table.insert fills test[1], and not test["1"].

So use test[1].

Would;

print(test.tonumber(1))

also work instead?

Nope. That would call a function stored in

test["tonumber"]

. But

test[tonumber(1)]

would work.

EDIT: tonumber(1) is still 1.

Is there any easy way to remove characters from a string? I know you can use string.sub() on everything else.
Also is there any easy way to do;

variable = variable + 1

similar to how you do;

variable++;

in Java?

you could use gsub to replace characters… gsub allows for an amount to replace to be set as well… read more on it here http://lua-users.org/wiki/StringLibraryTutorial

sadly there is no ++ operator.