Lua Frequently Asked Questions (FAQ)

• 1.1 Where to start?

• 1.2 Suitability as a first programming language?

• 1.3 Suitability as a second programming language?

• 1.4 Any good editors and debuggers?

• 1.5 Lua seems very verbose. Why isn't it like C?

• 1.6 How can undefined variable access be caught in Lua?

• 1.7 Does Lua support Unicode?

• 1.8 Optimization tips?

• 1.9 When do I need to worry about memory?

• 1.10 What is the difference between pairs and ipairs?

• 1.11 Why have a special operator for string concatenation?

• 1.12 I have seen Lua code with functions like strfind; why doesn't it work?

• 1.13 Why doesn't 'for k,v in t do' work anymore?

• 1.14 How can one put a nil value in an array?

• 1.15 How can I dump out a table?

• 1.16 Why does print 'hello' work, and not print 42?

• 1.17 What is the difference between a.f(x) and a:f(x)?

• 1.18 How are variables scoped?

• 1.19 Difference between require and dofile?

• 1.20 How to explicitly load a binary module?

• 1.21 What are function environments?

• 1.22 Can functions and operators be overloaded?

• 1.23 How to make functions receive a variable number of arguments?

• 1.24 How to return several values from a function?

• 1.25 Can you pass named parameters to a function?

• 1.26 Why is there no continue statement?

• 1.27 Is there any exception handling?

• 1.28 No classes? How do you guys survive?

• 1.28.1 What are closures?

• 1.29 Is there string Interpolation, for example in "$VAR is expanded"?

• 1.30 What are optimised tail calls useful for?

• 1.31 Packaging as a stand-alone application?

• 1.32 How do I load and run (potentially untrusted) Lua code?

• 1.33 Embedding Lua in an application?

• 1.34 Documenting Lua code?

• 1.35 How to check function argument types?

• 1.36 How to end script execution gracefully?

• 1.37 How does module() work?

• 1.38 What are weak tables?

• 1.39 What is the difference between the various ways to quote strings?

• 1.40 Compatibility issues between Windows and Unix?

• 2.1 How do I access command-line arguments?

• 2.2 How to Parse command-Line arguments?

• 2.3 How to read all the lines in a file?

• 2.4 How to read numbers?

• 2.5 How to format text and numbers nicely?

• 2.6 How to read CSV data?

• 2.7 How to work with binary data?

• 2.8 Are there regular expression libraries?

• 2.9 Parsing complex structured text data?

• 2.10 Are there mathematical libraries like complex numbers, higher-precision arithmetic, matrices, etc?

• 2.11 How to parse XML documents?

• 2.12 How to interface with databases?

• 2.13 Persisting program state?

• 3.1 How to get the current date and time?

• 3.2 How to execute an external command?

• 3.3 How to make a script pause for a few seconds?

• 3.4 How to list the contents of a directory? Ask for file properties?

• 3.5 Running a program as a Service/Daemon?

• 3.6 Has Lua got threads?

• 3.7 How to access the Windows registry?

• 3.8 Sending an email?

• 3.9 Can Lua be used as a Web scripting language?

• 3.10 Measuring elapsed time in a program?

• 4.1 It's a compact language, but I need more libraries. Where to find them?

• 4.2 What GUI toolkits are available?

• 4.3 Rendering graphics and plots to a file?

• 4.4 How to interface to my C/C++ libraries?

• 4.5 Is there a foreign function Interface (FFI)?

• 5.1 Smart Phones

• 5.2 What are the minimum requirements for an embedded device?

• 6.1 LuaJIT is significantly faster than vanilla Lua. What's the catch?

• 6.2 Using Lua with .NET, Java or Objective-C?

• 6.3 I miss all those Python/Perl libraries; can I access them?

• 6.4 Can Lua interoperate with CORBA or Web Services?

• 7.1 How do I traverse a Lua table?

• 7.2 How would I save a Lua table or a function for later use?

• 7.3 How can I create a multi-dimensional table in C?

• 7.4 Can I use C++ exceptions?

• 7.5 How to bind a C++ class to Lua?

• 7.6 What's the difference between the lua and the luaL functions?

• 7.7 What am I allowed to do with the Lua stack and its contents in my C functions?

• 7.8 What is the difference between userdata and light userdata?

• 8.1 What Lua 5.1 code breaks in Lua 5.2?

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