-- Lua script for QR code scanning

-- Function to capture an image from the webcam (placeholder)
local function capture_image(image_path)
    -- Your code to capture an image using external tools or libraries
end

-- Function to scan QR codes from an image file (unchanged)
local function scan_qr(image_path)
    local qr = qrscanner.qrcode()
    local status, err = qr:decode(image_path)
    if status then
        print("QR Code content: " .. status)
    else
        print("Error decoding QR Code: " .. err)
    end
end

-- Main function (unchanged)
local function main()
    local temp_dir = "temp_images"
    -- Create a temporary directory to save captured images
    os.execute("mkdir " .. temp_dir)

    while true do
        -- Capture an image from the webcam
        local image_path = temp_dir .. "/image.jpg"
        capture_image(image_path)

        -- Scan QR code from the captured image
        scan_qr(image_path)

        -- Wait for a while before capturing the next image
        socket.sleep(1)
    end
end

-- Call the main function
main()

Lua online compiler

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Taking inputs (stdin)

OneCompiler's Lua online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample Lua program which takes name as input and prints hello message with your name.

name = io.read("*a")
print ("Hello ", name)

About Lua

Lua is a light weight embeddable scripting language which is built on top of C. It is used in almost all kind of applications like games, web applications, mobile applications, image processing etc. It's a very powerful, fast, easy to learn, open-source scripting language.

Syntax help

Variables

  • By default all the variables declared are global variables
  • If the variables are explicitly mentioned as local then they are local variables.
  • Lua is a dynamically typed language and hence only the values will have types not the variables.

Examples

-- global variables
a = 10

-- local variables

local x = 30
Value TypeDescription
numberRepresents numbers
stringRepresents text
nilDifferentiates values whether it has data or not
booleanValue can be either true or false
functionRepresents a sub-routine
userdataRepresents arbitary C data
threadRepresents independent threads of execution.
tableCan hold any value except nil

Loops

1. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition)
do
--code
end

2. Repeat-Until:

Repeat-Until is also used to iterate a set of statements based on a condition. It is very similar to Do-While, it is mostly used when you need to execute the statements atleast once.

repeat
   --code
until( condition )

3. For:

For loop is used to iterate a set of statements based on a condition.

for init,max/min value, increment
do
   --code
end

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increase re-usuability and modularity.

optional_function_scope function function_name( argument1, argument2, argument3........, argumentn)
--code
return params with comma seperated
end