Lua 5.1 Reference Manual

https://lua.org/manual/5.1
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The official reference manual defining the Lua 5.1 programming language, covering its syntax,...
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### Example Function Definitions

Source: https://lua.org/manual/5.1/manual.html

Provides example function definitions to illustrate parameter handling and variadic arguments.

```lua
function f(a, b) end
```

```lua
function g(a, b, ...) end
```

```lua
function r() return 1,2,3 end
```

--------------------------------

### C Path Template Example

Source: https://lua.org/manual/5.1/manual.html

This example shows a typical C path configuration for `require`. It lists potential locations and file extensions for C libraries, using '.' for the current directory and '?' as a placeholder for the module name.

```lua
"./?.so;./?.dll;/usr/local/?/init.so"
```

--------------------------------

### Lua Path Template Example

Source: https://lua.org/manual/5.1/manual.html

This example demonstrates the format of a Lua path, which is a sequence of templates separated by semicolons. Each template can contain an interrogation mark '?' which is replaced by the module name.

```lua
"./?.lua;./?.lc;/usr/local/?/init.lua"
```

--------------------------------

### Equivalent Table Initialization

Source: https://lua.org/manual/5.1/manual.html

Shows the expanded form of the table constructor example, demonstrating sequential assignment.

```lua
     do
       local t = {}
       t[f(1)] = g
       t[1] = "x"         -- 1st exp
       t[2] = "y"         -- 2nd exp
       t.x = 1            -- t["x"] = 1
       t[3] = f(x)        -- 3rd exp
       t[30] = 23
       t[4] = 45          -- 4th exp
       a = t
     end
```

--------------------------------

### Lua Assignment Example

Source: https://lua.org/manual/5.1/manual.html

Demonstrates how multiple assignments work, including value adjustment and the order of evaluation.

```lua
i = 3
i, a[i] = i+1, 20
```

--------------------------------

### Lua Table Constructor Example

Source: https://lua.org/manual/5.1/manual.html

Illustrates how a complex table constructor is equivalent to a sequence of table assignments.

```lua
     a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 }
```

--------------------------------

### Vararg Function Call Examples

Source: https://lua.org/manual/5.1/manual.html

Illustrates how arguments are mapped to parameters and the vararg expression for different function calls.

```lua
CALL            PARAMETERS

f(3)             a=3, b=nil
f(3, 4)          a=3, b=4
f(3, 4, 5)       a=3, b=4
f(r(), 10)       a=1, b=10
f(r())           a=1, b=2

g(3)             a=3, b=nil, ... -->  (nothing)
g(3, 4)          a=3, b=4,   ... -->  (nothing)
g(3, 4, 5, 8)    a=3, b=4,   ... -->  5  8
g(5, r())        a=5, b=1,   ... -->  2  3
```

--------------------------------

### Lua Numerical Constant Examples

Source: https://lua.org/manual/5.1/manual.html

Illustrates valid numerical constants in Lua, including decimal, exponential, and hexadecimal formats.

```lua
3   3.0   3.1416   314.16e-2   0.31416E1   0xff   0x56
```

--------------------------------

### Get Lua Function Information

Source: https://lua.org/manual/5.1/manual.html

Retrieves information about a specific function or function invocation. Use 'what' to specify the desired fields. For function information, push the function onto the stack and start 'what' with '>'.

```c
int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);
```

```c
     lua_Debug ar;
     lua_getfield(L, LUA_GLOBALSINDEX, "f");  /* get global 'f' */
     lua_getinfo(L, ">S", &ar);
     printf("%d\n", ar.linedefined);

```

--------------------------------

### Coroutine Example in Lua

Source: https://lua.org/manual/5.1/manual.html

Demonstrates the creation and execution of coroutines using `coroutine.create`, `coroutine.resume`, and `coroutine.yield`. Shows how values are passed between the main thread and the coroutine body, and how errors are handled.

```lua
function foo (a)
  print("foo", a)
  return coroutine.yield(2*a)
end

co = coroutine.create(function (a,b)
      print("co-body", a, b)
      local r = foo(a+1)
      print("co-body", r)
      local r, s = coroutine.yield(a+b, a-b)
      print("co-body", r, s)
      return b, "end"
end)
        
print("main", coroutine.resume(co, 1, 10))
print("main", coroutine.resume(co, "r"))
print("main", coroutine.resume(co, "x", "y"))
print("main", coroutine.resume(co, "x", "y"))

```

--------------------------------

### Lua String Literal Examples

Source: https://lua.org/manual/5.1/manual.html

Demonstrates various ways to define string literals in Lua, including escape sequences and long bracket notation.

```lua
a = 'alo\n123"'
a = "alo\n123\""
a = '\97lo\10\04923"'
a = [[alo
123"]]
a = [==[
alo
123"]==]
```

--------------------------------

### Operating System Facilities

Source: https://lua.org/manual/5.1/manual.html

Functions for interacting with the operating system, such as getting CPU time.

```APIDOC
## `os.clock ()`

### Description
Returns an approximation of the amount in seconds of CPU time used by the program.

### Method
`os.clock`

### Response Example
```json
{
  "cpu_time_seconds": 1.234
}
```
```

--------------------------------

### Making Lua Scripts Executable

Source: https://lua.org/manual/5.1/manual.html

Provides examples of the shebang line for making Lua scripts executable on Unix-like systems. Using '#!/usr/bin/env lua' is a more portable solution.

```bash
#!/usr/local/bin/lua
```

```bash
#!/usr/bin/env lua
```

--------------------------------

### Lua Argument Table Example

Source: https://lua.org/manual/5.1/manual.html

Illustrates how command-line arguments are populated into the global 'arg' table when using the Lua interpreter. Arguments before the script name are stored at negative indices.

```lua
arg = { [-2] = "lua", [-1] = "-la",
        [0] = "b.lua",
        [1] = "t1", [2] = "t2" }
```

--------------------------------

### String formatting with substitutions

Source: https://lua.org/manual/5.1/errata.html

Example of using `string.gsub` to perform string substitutions, replacing patterns with values from a table. The pattern `$%w+` captures sequences of word characters.

```lua
x = string.gsub("$name-$%version.tar.gz", "%$(%w+)", t)
```

--------------------------------

### Lua Logical Operator Examples

Source: https://lua.org/manual/5.1/manual.html

Demonstrates the behavior of 'and' and 'or' operators, including short-circuit evaluation. Both 'false' and 'nil' are treated as false.

```lua
10 or 20            --> 10
     10 or error()       --> 10
     nil or "a"          --> "a"
     nil and 10          --> nil
     false and error()   --> false
     false and nil       --> false
     false or nil        --> nil
     10 and 20           --> 20
```

--------------------------------

### Load File as Lua Chunk with luaL_loadfile

Source: https://lua.org/manual/5.1/manual.html

Loads a file as a Lua chunk. Uses `lua_load` internally. Handles standard input if `filename` is NULL. Ignores the first line if it starts with '#'.

```c
int luaL_loadfile (lua_State *L, const char *filename);
```

--------------------------------

### Get Local Variable Information

Source: https://lua.org/manual/5.1/manual.html

Retrieves the name and value of a local variable at a specific index for a given stack level. Returns nil if the index is out of range. Variable names starting with '(' are internal.

```lua
debug.getlocal(level, local)
```

--------------------------------

### Get Lua Type Name

Source: https://lua.org/manual/5.1/manual.html

Use `lua_typename` to get the string name of a Lua type, given its integer code. The type code must be one returned by `lua_type`.

```c
const char *lua_typename  (lua_State *L, int tp);
```

--------------------------------

### luaL_buffinit

Source: https://lua.org/manual/5.1/manual.html

Initializes a string buffer.

```APIDOC
## luaL_buffinit

### Description
Initializes a buffer `B`. This function does not allocate any space; the buffer must be declared as a variable (see `luaL_Buffer`).

### Method
N/A (C function)

### Endpoint
N/A (C function)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
```c
luaL_Buffer b;
luaL_buffinit(L, &b);
```

### Response
#### Success Response (200)
None

#### Response Example
None
```

--------------------------------

### Get Function Information

Source: https://lua.org/manual/5.1/manual.html

Retrieves information about a function or a stack level. Use 'f' to include the function itself and 'L' for valid line numbers. The default is to get all available info except line numbers.

```lua
debug.getinfo(1, "n").name
```

```lua
debug.getinfo(print)
```

--------------------------------

### Get Object Length in Lua

Source: https://lua.org/manual/5.1/manual.html

Use `lua_objlen` to get the length of a value at a given stack index. For strings, it's the length; for tables, it's the result of the `#` operator; for userdata, it's the memory block size; otherwise, it's 0.

```c
size_t lua_objlen (lua_State *L, int index);
```

--------------------------------

### Open All Standard Lua Libraries

Source: https://lua.org/manual/5.1/manual.html

Opens all standard Lua libraries, making them available to the Lua state. This is the recommended way to include the standard library.

```c
luaL_openlibs(L);
```

--------------------------------

### Load and Run a String in Lua

Source: https://lua.org/manual/5.1/manual.html

Use this idiom to load and immediately run a Lua string. Ensure the string is valid Lua code; otherwise, `assert` will raise an error.

```lua
assert(loadstring(s))()
```

--------------------------------

### Object Length

Source: https://lua.org/manual/5.1/manual.html

Function to get the length of a Lua object.

```APIDOC
## `lua_objlen`

### Description
Returns the "length" of the value at the given acceptable index: for strings, this is the string length; for tables, this is the result of the length operator ('`#`'); for userdata, this is the size of the block of memory allocated for the userdata; for other values, it is 0.

### Method
`size_t lua_objlen (lua_State *L, int index);
`

### Parameters
- **L** (`lua_State *`) - The Lua state.
- **index** (`int`) - The index of the value on the stack.

### Request Example
```c
size_t lua_objlen (lua_State *L, int index);
```

### Response
- **`size_t`**: The length of the value.
```

--------------------------------

### Get Metatable

Source: https://lua.org/manual/5.1/manual.html

Returns the metatable associated with an object, or nil if none exists.

```lua
debug.getmetatable(object)
```

--------------------------------

### Prepare Buffer for String Addition

Source: https://lua.org/manual/5.1/manual.html

Prepares a buffer of LUAL_BUFFERSIZE for copying a string to be added to a luaL_Buffer. Must be followed by luaL_addsize.

```c
char *luaL_prepbuffer (luaL_Buffer *B);
```

--------------------------------

### Get CPU Time

Source: https://lua.org/manual/5.1/manual.html

Returns an approximation of the CPU time used by the program in seconds.

```lua
os.clock ()
```

--------------------------------

### dofile

Source: https://lua.org/manual/5.1/manual.html

Opens and executes a Lua chunk from a file.

```APIDOC
## `dofile ([filename])`

### Description
`dofile` is similar to `loadfile`, but it also calls the resulting function in the Lua state. It opens the named file, compiles the contents as a Lua chunk, and then runs the chunk. `dofile` returns any values returned by the chunk. If the file is not found or cannot be opened, `dofile` raises an error. If called without arguments, `dofile` executes the contents of `stdin`.

### Parameters
- **filename** (string, optional): The path to the Lua file to execute.

### Returns
- The values returned by the executed Lua chunk.

### Errors
- Raises an error if the file cannot be opened or compiled.

### Example
```lua
-- Assuming 'my_script.lua' exists and contains 'print("Hello from dofile!")'
dofile("my_script.lua") -- Output: Hello from dofile!

-- Execute code from standard input
-- dofile() 
```
```

--------------------------------

### Get Lua Version

Source: https://lua.org/manual/5.1/manual.html

This global variable holds the current Lua version string.

```lua
_VERSION
```

--------------------------------

### luaL_dofile

Source: https://lua.org/manual/5.1/manual.html

Loads and runs a Lua file.

```APIDOC
## luaL_dofile

### Description
Loads and runs the given file. It is defined as the following macro: `(luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0))`. It returns 0 if there are no errors or 1 in case of errors.

### Method
N/A (C function)

### Endpoint
N/A (C function)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response (200)
Returns 0 on success, 1 on error.

#### Response Example
N/A
```

--------------------------------

### Raw Get Value in Lua

Source: https://lua.org/manual/5.1/manual.html

Retrieves the value of `table[index]` without invoking metamethods.

```lua
rawget(table, index)
```

--------------------------------

### Open a File

Source: https://lua.org/manual/5.1/manual.html

Opens a file with the specified mode ('r', 'w', 'a', 'r+', 'w+', 'a+'). A 'b' can be appended for binary mode. Returns a file handle or nil on error.

```lua
io.open ("file.txt", "r")
```

```lua
io.open ("file.txt", "wb")
```

--------------------------------

### Get the Metatable of an Object

Source: https://lua.org/manual/5.1/manual.html

Retrieves the metatable associated with an object. Returns nil if the object has no metatable.

```lua
getmetatable (object)
```

--------------------------------

### Open Standard Lua Libraries with luaL_openlibs

Source: https://lua.org/manual/5.1/manual.html

Loads all standard Lua libraries into the provided Lua state.

```c
void luaL_openlibs (lua_State *L);
```

--------------------------------

### Load and Run File with luaL_dofile

Source: https://lua.org/manual/5.1/manual.html

Executes a Lua file. This is a macro that combines `luaL_loadfile` and `lua_pcall`. Returns 0 on success, 1 on error.

```c
int luaL_dofile (lua_State *L, const char *filename);
```

```c
(luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0))
```

--------------------------------

### luaL_dostring

Source: https://lua.org/manual/5.1/manual.html

Loads and runs a Lua string.

```APIDOC
## luaL_dostring

### Description
Loads and runs the given string. It is defined as the following macro: `(luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0))`. It returns 0 if there are no errors or 1 in case of errors.

### Method
N/A (C function)

### Endpoint
N/A (C function)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response (200)
Returns 0 on success, 1 on error.

#### Response Example
N/A
```

--------------------------------

### Executing Lua Strings with Options

Source: https://lua.org/manual/5.1/manual.html

Demonstrates executing multiple Lua strings sequentially using the -e option. The interpreter processes these options in order before running the specified script.

```bash
$ lua -e'a=1' -e 'print(a)' script.lua
```

--------------------------------

### Get Registry Table

Source: https://lua.org/manual/5.1/manual.html

Returns the global registry table, which holds Lua's internal state.

```lua
debug.getregistry()
```

--------------------------------

### Get Metatable by Name with luaL_getmetatable

Source: https://lua.org/manual/5.1/manual.html

Pushes the metatable associated with a given name from the registry onto the stack.

```c
void luaL_getmetatable (lua_State *L, const char *tname);
```

--------------------------------

### debug.setupvalue

Source: https://lua.org/manual/5.1/manual.html

Assigns a value to an upvalue of a function.

```APIDOC
## `debug.setupvalue (func, up, value)`

### Description
This function assigns the value `value` to the upvalue with index `up` of the function `func`. The function returns **nil** if there is no upvalue with the given index. Otherwise, it returns the name of the upvalue.
```

--------------------------------

### Check and Get String Argument

Source: https://lua.org/manual/5.1/manual.html

Verifies if the argument at `narg` is a string and returns it. Uses `lua_tolstring` internally.

```c
const char *luaL_checkstring (lua_State *L, int narg);
```

--------------------------------

### luaL_prepbuffer

Source: https://lua.org/manual/5.1/manual.html

Prepares a buffer for string concatenation by returning a pointer to a writable space.

```APIDOC
## luaL_prepbuffer

### Description
Returns an address to a space of size `LUAL_BUFFERSIZE` where you can copy a string to be added to buffer `B` (see `luaL_Buffer`). After copying the string into this space you must call `luaL_addsize` with the size of the string to actually add it to the buffer.

### Method
C Function

### Endpoint
N/A (C API Function)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response (char *)
- Returns a pointer to a character array (buffer space) of size `LUAL_BUFFERSIZE`.

#### Response Example
N/A
```

--------------------------------

### Get String Length with string.len

Source: https://lua.org/manual/5.1/manual.html

Calculates the length of a string. It correctly handles strings containing null characters.

```lua
string.len("")
""
```

```lua
string.len("a\000bc\000")
"a\000bc\000"
```

--------------------------------

### Get Type Name of a Value

Source: https://lua.org/manual/5.1/manual.html

Returns the string name of the type of the Lua value at the specified stack index.

```c
const char *luaL_typename (lua_State *L, int index);
```

--------------------------------

### Lua Syntactic Sugar for Function Definitions

Source: https://lua.org/manual/5.1/manual.html

Illustrates the syntactic sugar available for defining functions and local functions in Lua.

```lua
stat ::= **function** funcname funcbody
```

```lua
stat ::= **local** **function** Name funcbody
```

```lua
funcname ::= Name {`**.**´ Name} [`**:**´ Name]
```

--------------------------------

### Check and Get Number Argument

Source: https://lua.org/manual/5.1/manual.html

Verifies if the argument at `narg` is a number and returns it as a `lua_Number`. Raises an error if the type is incorrect.

```c
lua_Number luaL_checknumber (lua_State *L, int narg);
```

--------------------------------

### Create New Metatable with luaL_newmetatable

Source: https://lua.org/manual/5.1/manual.html

Creates a new table for userdata metatables and registers it under `tname`. Pushes the metatable onto the stack. Returns 1 if a new table was created, 0 otherwise.

```c
int luaL_newmetatable (lua_State *L, const char *tname);
```

--------------------------------

### Check and Get Integer Argument

Source: https://lua.org/manual/5.1/manual.html

Verifies if the argument at `narg` is a number and returns it as an `int`. Raises an error if the type is incorrect.

```c
int luaL_checkint (lua_State *L, int narg);
```

--------------------------------

### Create and Return a Reference

Source: https://lua.org/manual/5.1/manual.html

Creates a reference to an object on the stack within a given table and returns a unique integer key for it. Pops the object from the stack. Returns LUA_REFNIL for nil objects.

```c
int luaL_ref (lua_State *L, int t);
```

--------------------------------

### Get Upvalue Information

Source: https://lua.org/manual/5.1/manual.html

Retrieves the name and value of an upvalue for a given function and upvalue index. Returns nil if the index is invalid.

```lua
debug.getupvalue(func, up)
```

--------------------------------

### _G

Source: https://lua.org/manual/5.1/manual.html

Represents the global environment table in Lua.

```APIDOC
## `_G`

### Description
`_G` is a global variable that holds the global environment table. All global variables are stored as fields in this table. By default, `_G._G = _G`, meaning the global environment table refers to itself.

### Usage
Modifying `_G` can affect global variables and the behavior of functions that rely on the global environment. It is generally not recommended to modify `_G` directly unless you have a specific reason, such as implementing custom global environments or using `setfenv` (which is deprecated in favor of `_ENV`).

### Example
```lua
-- Accessing a global variable through _G
print(_G.print)

-- Assigning a new global variable
_G.my_global = 100
print(my_global) -- Output: 100
```
```

--------------------------------

### Check and Get Long Integer Argument

Source: https://lua.org/manual/5.1/manual.html

Verifies if the argument at `narg` is a number and returns it as a `long`. Raises an error if the type is incorrect.

```c
long luaL_checklong (lua_State *L, int narg);
```

--------------------------------

### Check and Get Lua Integer Argument

Source: https://lua.org/manual/5.1/manual.html

Verifies if the argument at `narg` is a number and returns it as a `lua_Integer`. Raises an error if the type is incorrect.

```c
lua_Integer luaL_checkinteger (lua_State *L, int narg);
```

--------------------------------

### Get Lua Hook Mask

Source: https://lua.org/manual/5.1/manual.html

Retrieves the current hook mask of the Lua state. This indicates which events trigger debug hooks.

```c
int lua_gethookmask (lua_State *L);
```

--------------------------------

### Get Current Hook Function

Source: https://lua.org/manual/5.1/manual.html

Retrieves the currently set hook function for the Lua state. Hooks are used for debugging and profiling.

```c
lua_Hook lua_gethook (lua_State *L);
```

--------------------------------

### Create New Lua State with luaL_newstate

Source: https://lua.org/manual/5.1/manual.html

Initializes a new Lua state using `realloc` as the allocator and sets a default panic function.

```c
lua_State *luaL_newstate (void);
```

--------------------------------

### lua_createtable

Source: https://lua.org/manual/5.1/manual.html

Creates a new empty table and pushes it onto the Lua stack. It allows for pre-allocation of space for array and non-array elements, which can improve performance if the table size is known in advance.

```APIDOC
## lua_createtable

### Description
Creates a new empty table and pushes it onto the stack. The new table has space pre-allocated for `narr` array elements and `nrec` non-array elements. This pre-allocation is useful when you know exactly how many elements the table will have. Otherwise you can use the function `lua_newtable`.

### Method
`void lua_createtable (lua_State *L, int narr, int nrec);
`

### Stack
[-0, +1, _m_]

### Parameters
- **L** (*lua_State*) - The Lua state.
- **narr** (*int*) - The number of elements to pre-allocate for the array part.
- **nrec** (*int*) - The number of elements to pre-allocate for the non-array part.
```

--------------------------------

### Get environment table in Lua

Source: https://lua.org/manual/5.1/errata.html

The `getfenv` function retrieves the environment table of a given function or the current function if no argument is provided.

```lua
getfenv ([f])
```

--------------------------------

### luaL_newstate

Source: https://lua.org/manual/5.1/manual.html

Creates a new Lua state.

```APIDOC
## luaL_newstate

### Description
Creates a new Lua state. It calls `lua_newstate` with an allocator based on the standard C `realloc` function and then sets a panic function (see `lua_atpanic`) that prints an error message to the standard error output in case of fatal errors. Returns the new state, or `NULL` if there is a memory allocation error.

### Method
N/A (C function)

### Endpoint
N/A (C function)

### Parameters
#### Path Parameters
N/A

#### Query Parameters
N/A

#### Request Body
N/A

### Request Example
N/A

### Response
#### Success Response (200)
Returns a pointer to the new Lua state.

#### Response Example
N/A
```

--------------------------------

### Get Metatable Field with luaL_getmetafield

Source: https://lua.org/manual/5.1/manual.html

Retrieves a field from an object's metatable. Returns 0 and pushes nothing if the metatable or field is absent.

```c
int luaL_getmetafield (lua_State *L, int obj, const char *e);
```

--------------------------------

### lua_setupvalue

Source: https://lua.org/manual/5.1/manual.html

Sets the value of a closure's upvalue.

```APIDOC
## `lua_setupvalue`

### Description
Sets the value of a closure's upvalue. The new value is taken from the top of the stack.

### Method
`const char *lua_setupvalue (lua_State *L, int funcindex, int n);
`

### Parameters
- **L** (`lua_State *`) - The Lua state.
- **funcindex** (`int`) - The index of the closure in the stack.
- **n** (`int`) - The index of the upvalue.

### Returns
- The name of the upvalue if successful.
- `NULL` if the index is invalid, and the stack is not modified.
```

--------------------------------

### debug.getregistry ()

Source: https://lua.org/manual/5.1/manual.html

Returns the registry table.

```APIDOC
## debug.getregistry ()

### Description
Returns the registry table (see §3.5).

### Method
Call

### Endpoint
N/A (Internal function)
```

--------------------------------

### Register Lua Library Functions

Source: https://lua.org/manual/5.1/manual.html

Opens a Lua library by registering a list of C functions. It can register functions into the top table or create/update a global library.

```c
void luaL_register (lua_State *L,
                    const char *libname,
                    const luaL_Reg *l);
```

--------------------------------

### Get Optional String Argument

Source: https://lua.org/manual/5.1/manual.html

Retrieves a string argument by its index. Returns a default string if the argument is nil or absent. Raises an error for other types.

```c
const char *luaL_optstring (lua_State *L,
                            int narg,
                            const char *d);
```

--------------------------------

### Get Optional Number Argument

Source: https://lua.org/manual/5.1/manual.html

Retrieves a number argument by its index. Returns a default value if the argument is nil or absent. Raises an error for other types.

```c
lua_Number luaL_optnumber (lua_State *L, int narg, lua_Number d);
```

--------------------------------

### Set File Buffering Mode

Source: https://lua.org/manual/5.1/manual.html

Configures the buffering for an output file. 'no' for no buffering, 'full' for full buffering, and 'line' for line buffering. An optional size can be specified.

```lua
file:setvbuf ("no")
```

```lua
file:setvbuf ("full", 1024)
```

```lua
file:setvbuf ("line")
```

--------------------------------

### Get Optional Integer Argument

Source: https://lua.org/manual/5.1/manual.html

Retrieves an integer argument by its index. Returns a default value if the argument is nil or absent. Raises an error for other types.

```c
lua_Integer luaL_optinteger (lua_State *L,
                             int narg,
                             lua_Integer d);
```

--------------------------------

### lua_pushvfstring

Source: https://lua.org/manual/5.1/manual.html

Equivalent to `lua_pushfstring`, but accepts a `va_list` for arguments.

```APIDOC
## lua_pushvfstring

### Description
Equivalent to `lua_pushfstring`, except that it receives a `va_list` instead of a variable number of arguments.

### Method
`const char *lua_pushvfstring (lua_State *L, const char *fmt, va_list argp);
`

### Parameters
#### Path Parameters
- **L** (`lua_State *`) - Required - The Lua state.
- **fmt** (`const char *`) - Required - The format string.
- **argp** (`va_list`) - Required - The variable arguments list.

### Response Example
```json
{
  "formatted_string": "example string"
}
```
```

--------------------------------

### Create a Temporary File

Source: https://lua.org/manual/5.1/manual.html

Returns a file handle for a temporary file opened in update mode. The file is automatically removed when the program ends.

```lua
io.tmpfile ()
```

--------------------------------

### Get Optional Integer Argument with luaL_optint

Source: https://lua.org/manual/5.1/manual.html

Retrieves an integer argument, returning a default value if the argument is absent or nil. Raises an error for other types.

```c
int luaL_optint (lua_State *L, int narg, int d);
```

--------------------------------

### Get Current Hook Count

Source: https://lua.org/manual/5.1/manual.html

Retrieves the current hook count, which determines how often the hook function is called (e.g., every N instructions).

```c
int lua_gethookcount (lua_State *L);
```

--------------------------------

### Load and Run String with luaL_dostring

Source: https://lua.org/manual/5.1/manual.html

Executes a Lua string. This is a macro that combines `luaL_loadstring` and `lua_pcall`. Returns 0 on success, 1 on error.

```c
int luaL_dostring (lua_State *L, const char *str);
```

```c
(luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0))
```

--------------------------------

### Lua Pattern Matching

Source: https://lua.org/manual/5.1/manual.html

Explains the syntax and components of Lua's pattern matching, including character classes, repetition modifiers, captures, and anchoring.

```APIDOC
## Pattern Item
A _pattern item_ can be:
  * a single character class, which matches any single character in the class;
  * a single character class followed by '`*`', which matches 0 or more repetitions of characters in the class. These repetition items will always match the longest possible sequence;
  * a single character class followed by '`+`', which matches 1 or more repetitions of characters in the class. These repetition items will always match the longest possible sequence;
  * a single character class followed by '`-`', which also matches 0 or more repetitions of characters in the class. Unlike '`*`', these repetition items will always match the _shortest_ possible sequence;
  * a single character class followed by '`?`', which matches 0 or 1 occurrence of a character in the class;
  * `%_n_`, for _n_ between 1 and 9; such item matches a substring equal to the _n_ -th captured string.
  * `%b_xy_`, where _x_ and _y_ are two distinct characters; such item matches strings that start with _x_, end with _y_, and where the _x_ and _y_ are _balanced_.

## Pattern
A _pattern_ is a sequence of pattern items. A '`^`' at the beginning of a pattern anchors the match at the beginning of the subject string. A '`$`' at the end of a pattern anchors the match at the end of the subject string. At other positions, '`^`' and '`$`' have no special meaning and represent themselves.

## Captures
A pattern can contain sub-patterns enclosed in parentheses; they describe _captures_. When a match succeeds, the substrings of the subject string that match captures are stored (_captured_) for future use. Captures are numbered according to their left parentheses. For instance, in the pattern `"(a*(.)%w(%s*))"`, the part of the string matching `"a*(.)%w(%s*)"` is stored as the first capture (and therefore has number 1); the character matching "." is captured with number 2, and the part matching "`%s*`" has number 3.
As a special case, the empty capture `()` captures the current string position (a number). For instance, if we apply the pattern `"()aa()"` on the string `"flaaap"`, there will be two captures: 3 and 5.
A pattern cannot contain embedded zeros. Use `%z` instead.
```

--------------------------------

### Get Lua Value Type

Source: https://lua.org/manual/5.1/manual.html

Use `lua_type` to determine the data type of a value at a specific stack index. Returns `LUA_TNONE` for invalid indices.

```c
int lua_type (lua_State *L, int index);
```

--------------------------------

### Lua Method Call Syntax

Source: https://lua.org/manual/5.1/manual.html

Illustrates the syntax for calling methods in Lua. This is syntactic sugar for accessing a field and then calling it as a function with the object as the first argument.

```lua
functioncall ::= prefixexp ":" Name args
```

--------------------------------

### Get Optional Long Argument

Source: https://lua.org/manual/5.1/manual.html

Retrieves a long integer argument by its index. Returns a default value if the argument is nil or absent. Raises an error for other types.

```c
long luaL_optlong (lua_State *L, int narg, long d);
```

--------------------------------

### Table Creation

Source: https://lua.org/manual/5.1/manual.html

Functions for creating new tables in Lua.

```APIDOC
## `lua_newtable`

### Description
Creates a new empty table and pushes it onto the stack. It is equivalent to `lua_createtable(L, 0, 0)`.

### Method
`void lua_newtable (lua_State *L);`

### Parameters
None

### Request Example
```c
void lua_newtable (lua_State *L);
```

### Response
None
```

--------------------------------

### Lua Raw Table Get Function

Source: https://lua.org/manual/5.1/manual.html

Performs a raw table access without invoking metamethods. Use when direct access to table elements is required.

```c
void lua_rawget (lua_State *L, int index);
```
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