Lua Programming Examples

while Loop in Lua

lua

a = 10

while( a < 20 )
do
   print("value of a:", a)
   a = a+1
end

Lua Operators Precedence

lua

a = 20
b = 10
c = 15
d = 5

e = (a + b) * c / d;-- ( 30 * 15 ) / 5
print("Value of (a + b) * c / d is   :",e )

e = ((a + b) * c) / d; -- (30 * 15 ) / 5
print("Value of ((a + b) * c) / d is :",e )

e = (a + b) * (c / d);-- (30) * (15/5)
print("Value of (a + b) * (c / d) is :",e )

e = a + (b * c) / d;  -- 20 + (150/5)
print("Value of a + (b * c) / d is   :",e )

Lua Relational Operators

lua

a = 21
b = 10

if( a == b )
then
   print("Line 1 - a is equal to b" )
else
   print("Line 1 - a is not equal to b" )
end

if( a ~= b )
then
   print("Line 2 - a is not equal to b" )
else
   print("Line 2 - a is equal to b" )
end

if ( a < b )
then
   print("Line 3 - a is less than b" )
else
   print("Line 3 - a is not less than b" )
end

if ( a > b ) 
then
   print("Line 4 - a is greater than b" )
else
   print("Line 5 - a is not greater than b" )
end

-- Lets change value of a and b
a = 5
b = 20

if ( a <= b ) 
then
   print("Line 5 - a is either less than or equal to  b" )
end

if ( b >= a ) 
then
   print("Line 6 - b is either greater than  or equal to b" )
end

Lua Arithmetic Operators

lua

a = 21
b = 10
c = a + b

print("Line 1 - Value of c is ", c )
c = a - b

print("Line 2 - Value of c is ", c )
c = a * b

print("Line 3 - Value of c is ", c )
c = a / b

print("Line 4 - Value of c is ", c )
c = a % b

print("Line 5 - Value of c is ", c )
c = a^2

print("Line 6 - Value of c is ", c )
c = -a

print("Line 7 - Value of c is ", c )

Data Types

lua

print(type("What is my type"))   --&gt; string
t = 10

print(type(5.8*t))               --&gt; number
print(type(true))                --&gt; boolean
print(type(print))               --&gt; function
print(type(nil))                 --&gt; nil
print(type(type(ABC)))           --&gt; string

Variable Declaration in Lua

lua

-- Variable definition:
local a, b

-- Initialization
a = 10
b = 30

print("value of a:", a)

print("value of b:", b)

-- Swapping of variables
b, a = a, b

print("value of a:", a)

print("value of b:", b)

f = 70.0/3.0
print("value of f", f)

Default Program

lua

#!/usr/local/bin/lua

print("test")

Test Program

lua

print("test")

Execute Lua Online

lua

local sentText = "abc"

function splitString(s)
	local t = {}
	for i = 1,s:len() do table.insert(t, s:sub(i,i)) end
	return t
end

function toByteForm(c) -- Izveido dotā burta baita reprezentaciju
	local byteString = "00000000"
	local i = c:byte()
	if i >= 128 then
		byteString = "10000000"
		i = i - 128
	end
	if i >= 64 then
		byteString = byteString:sub(1,1)..'1000000'
		i = i - 64
	end
	if i >= 32 then
		byteString = byteString:sub(1,2)..'100000'
		i = i - 32
	end
	if i >= 16 then
		byteString = byteString:sub(1,3)..'10000'
		i = i - 16
	end
	if i >= 8 then
		byteString = byteString:sub(1,4)..'1000'
		i = i - 8
	end
	if i >= 4 then
		byteString = byteString:sub(1,5)..'100'
		i = i - 4
	end
	if i >= 2 then
		byteString = byteString:sub(1,6)..'10'
		i = i - 2
	end
	if i >= 1 then
		byteString = byteString:sub(1,7)..'1'
	end
	return byteString
end

function printTable(t,indent) -- tiek drukāta tabula kopā ar tās iespējām. Tiek izmantota, lai pārbaudītu tabulu struktūru, kas rodas pēc gramatikas pieshkirshanas
	for k,v in pairs(t) do
		if type(v) == "table" then
			s = ""
			for i = 1, indent do s = s.." " end
			print (s..k..": ")
			printTable(v,indent+4)
		else
			s = ""
			for i = 1, indent do s = s.." " end
			print(s..k..":\t"..v)
		end
	end
end
--local t = splitString(sentText)
--for i,c in ipairs(t) do t[i] = toByteForm(c) end
--printTable(t,0)

function toCodeword(s) --s burts ir baita attēlojums
	local codeword = "__"..s:sub(1,1).."_"..s:sub(2,4).."_"..s:sub(5,8)
	local count1 = 0
	local count2 = 0
	local count3 = 0
	local count4 = 0
	if codeword:sub(3,3) == "1" then count1, count2 = count1 + 1, count2 + 1 end
	if codeword:sub(5,5) == "1" then count1, count3 = count1 + 1, count3 + 1 end
	if codeword:sub(6,6) == "1" then count3, count2 = count3 + 1, count2 + 1 end
	if codeword:sub(7,7) == "1" then count1, count2, count3 = count1 + 1, count2 + 1, count3 + 1 end
	if codeword:sub(9,9) == "1" then count1, count4 = count1 + 1, count4 + 1 end
	if codeword:sub(10,10) == "1" then count4, count2 = count4 + 1, count2 + 1 end
	if codeword:sub(11,11) == "1" then count1, count2, count4 = count1 + 1, count2 + 1, count4 + 1 end
	if codeword:sub(12,12) == "1" then count4, count3 = count4 + 1, count3 + 1 end
	count1 = count1 % 2
	count2 = count2 % 2
	count3 = count3 % 2
	count4 = count4 % 2
	codeword = count1..count2..s:sub(1,1)..count3..s:sub(2,4)..count4..s:sub(5,8)
	return codeword
end

function toTransmission(t)
	local transmissionString = ""
	for i = 1, 12 do
		for j, codeword in ipairs(t) do transmissionString = transmissionString..codeword:sub(i,i) end
		--transmissionString = transmissionString.." "
	end
	return transmissionString
end

function burstError(s) --ieviesh burstError random pozīcijai un garumam
	local firstErr = math.random(s:len() - (s:len()/6))
	--local lastErr = math.random(s:len() - firstErr) + firstErr
	local lastErr = math.random(s:len()/6) + firstErr --burstError nav garāks par 2n, kur n ir pārsūtītie koda vārdi
	print ("Transmisijas pirmā un pēdējā pārveidotā bita indekss:")
	print (firstErr, lastErr)
	return s:sub(1,firstErr-1)..flipBits(s:sub(firstErr, lastErr))..s:sub(lastErr+1)
end

function flipBits(s) -- s'ā apgriež visus bitus
	local s2 = ""
	for i = 1, s:len() do
		if s:sub(i,i) == "0" then s2 = s2.."1" else s2 = s2.."0" end
	end
	return s2
end

function transmissionToCodewords(s)
	local t = {}
	local cwCount = s:len() / 12
	for i = 1, cwCount do table.insert(t,"") end
	for i = 1, s:len() do
		local n = i % cwCount
		if n == 0 then n = cwCount end
		t[n] = t[n]..s:sub(i,i)
	end
	return t
end

function checkErrors(s) --s is Hamming codeword
	local errorLocation = 0
	local ones = {0,0,0,0}
	if s:sub(1,1) == '1' then ones[1] = ones[1] + 1 end
	if s:sub(2,2) == '1' then ones[2] = ones[2] + 1 end
	if s:sub(3,3) == '1' then ones[1], ones[2] = ones[1] + 1, ones[2] + 1 end
	if s:sub(4,4) == '1' then ones[3] = ones[3] + 1 end
	if s:sub(5,5) == '1' then ones[1], ones[3] = ones[1] + 1, ones[3] + 1 end
	if s:sub(6,6) == '1' then ones[2], ones[3] = ones[2] + 1, ones[3] + 1 end
	if s:sub(7,7) == '1' then ones[1], ones[2], ones[3] = ones[1] + 1, ones[2] + 1, ones[3] + 1 end
	if s:sub(8,8) == '1' then ones[4] = ones[4] + 1 end
	if s:sub(9,9) == '1' then ones[1], ones[4] = ones[1] + 1, ones[4] + 1 end
	if s:sub(10,10) == '1' then ones[2], ones[4] = ones[2] + 1, ones[4] + 1 end
	if s:sub(11,11) == '1' then ones[1], ones[2], ones[4] = ones[1] + 1, ones[2] + 1, ones[4] + 1 end
	if s:sub(12,12) == '1' then ones[3], ones[4] = ones[3] + 1, ones[4] + 1 end
	if ones[1] % 2 == 1 then errorLocation = errorLocation + 1 end
	if ones[2] % 2 == 1 then errorLocation = errorLocation + 2 end
	if ones[3] % 2 == 1 then errorLocation = errorLocation + 4 end
	if ones[4] % 2 == 1 then errorLocation = errorLocation + 8 end
	if errorLocation ~= 0 then
		if s:sub(errorLocation, errorLocation) == '0' then return s:sub(1,errorLocation-1)..'1'..s:sub(errorLocation+1) end
		if s:sub(errorLocation, errorLocation) == '1' then return s:sub(1,errorLocation-1)..'0'..s:sub(errorLocation+1) end
	end
	return s
end

function discardChecksums(s)
	return s:sub(3,3)..s:sub(5,7)..s:sub(9,12)
end

function byteFormToLetter(s)
	local c = 0;
	if s:sub(1,1) == '1' then c = c + 128 end
	if s:sub(2,2) == '1' then c = c + 64 end
	if s:sub(3,3) == '1' then c = c + 32 end
	if s:sub(4,4) == '1' then c = c + 16 end
	if s:sub(5,5) == '1' then c = c + 8 end
	if s:sub(6,6) == '1' then c = c + 4 end
	if s:sub(7,7) == '1' then c = c + 2 end
	if s:sub(8,8) == '1' then c = c + 1 end
	return string.char(c)
end

function combineString(t)
	local s = ""
	for i, letter in ipairs(t) do s = s..letter end
	return s
end

--printTable(transmissionToCodewords("aaabbbcccdddeeefffggghhhiiijjjkkklll"),0)

math.randomseed(os.time())
print ("Sūtāmā ziņa:")
print (sentText)
print ("\f")
local t = splitString(sentText)
for i,c in ipairs(t) do t[i] = toByteForm(c) end
print ("\f")
print ("Katra rindiņa ir ziņojuma baits:")
printTable(t,0)
print ("\f")
print ("Baiti pārveidoti uz Hamming kodu:")
for i,c in ipairs(t) do t[i] = toCodeword(c) end
printTable(t,0)
print ("\f") 
print ("Bitu pārraide (pārraušanas kļūdu apstrādei):")
local s = toTransmission(t)
print (s)
print ("\f")
s = burstError(s)
print ("\f")
print ("Bitu secība pēc nejauša garuma pārslēgšanās kļūdas ieviešanas [0; 2n], kur n ir sākotnējais ziņojuma garums baitos:")
print (s)
local t2 = transmissionToCodewords(s)
print ("\f") 
print ("Bitu secība sadalīta Hamminga kodu:")
printTable(t2,0)
for i, codeword in ipairs(t2) do t2[i] = checkErrors(codeword) end
print ("\f")
print ("Kods pēc labojumiem:")
printTable(t2,0)
for i, codeword in ipairs(t2) do t2[i] = discardChecksums(codeword) end
print ("\f")
print ("Ziņojuma baiti pēc visu pārbaudes bitu norakstīšanas:")
printTable(t2,0)
for i, byteForm in ipairs(t2) do t2[i] = byteFormToLetter(byteForm) end
print ("\f")
print ("Saņemtais ziņojums:")
print (combineString(t2))

Execute Lua Online

lua

a = "7n5m4m2p1d6"

function trenne(s, i, j)
    b = string.sub(s,i,j) 
    return b
end
i = 1
c = 0

while i < string.len(a) do
    x1 = tonumber(trenne(a, i, i))
    x2 = tonumber(trenne(a, i+2, i+2))
    if i < 3 then
        
        if trenne(a, i+1, i+1) == "p" then
          c = x1 + x2
        elseif trenne(a, i+1, i+1) == "m" then
          c = x1 - x2
        elseif trenne(a, i+1, i+1) == "n" then
          c = x1 * x2
        elseif trenne(a, i+1, i+1) == "d" then
          c = x1 / x2
        else
          print("invalid operation")
        end
        i = i +3
    else
        x1 = c
        x2 = tonumber(trenne(a,i+1,i+1))
        
        if trenne(a, i, i) == "p" then
          c = x1 + x2
        elseif trenne(a, i, i) == "m" then
          c = x1 - x2
        elseif trenne(a, i, i) == "n" then
          c = x1 * x2
        elseif trenne(a, i, i) == "d" then
          c = x1 / x2
        else
          print("invalid operation")
        end
        i = i +2
    end
end
print(c)

Follow

Newsletter