6 – Standard Libraries

The standard Lua libraries provide useful functions that are implemented directly through the C API. Some of these functions provide essential services to the language (e.g., type and getmetatable); others provide access to "outside" services (e.g., I/O); and others could be implemented in Lua itself, but are quite useful or have critical performance requirements that deserve an implementation in C (e.g., table.sort).

All libraries are implemented through the official C API and are provided as separate C modules. Currently, Lua has the following standard libraries:

  • basic library (§6.1);
  • coroutine library (§6.2);
  • package library (§6.3);
  • string manipulation (§6.4);
  • basic UTF-8 support (§6.5);
  • table manipulation (§6.6);
  • mathematical functions (§6.7) (sin, log, etc.);
  • input and output (§6.8);
  • operating system facilities (§6.9);
  • debug facilities (§6.10).

Except for the basic and the package libraries, each library provides all its functions as fields of a global table or as methods of its objects.

To have access to these libraries, the C host program should call the luaL_openlibs function, which opens all standard libraries. Alternatively, the host program can open them individually by using luaL_requiref to call luaopen_base (for the basic library), luaopen_package (for the package library), luaopen_coroutine (for the coroutine library), luaopen_string (for the string library), luaopen_utf8 (for the UTF8 library), luaopen_table (for the table library), luaopen_math (for the mathematical library), luaopen_io (for the I/O library), luaopen_os (for the operating system library), and luaopen_debug (for the debug library). These functions are declared in lualib.h.

math.tointeger()
  • References/Lua/Lua/Standard Libraries/Mathematical Functions

math.tointeger (x) If the value x is convertible to an integer, returns that integer. Otherwise, returns nil.

2025-01-10 15:47:30
os.time()
  • References/Lua/Lua/Standard Libraries/Operating System Facilities

os.time ([table]) Returns the current time when called without arguments, or a time representing the local date and time specified by the given table. This table must have fields

2025-01-10 15:47:30
math.mininteger
  • References/Lua/Lua/Standard Libraries/Mathematical Functions

math.mininteger

2025-01-10 15:47:30
rawset()
  • References/Lua/Lua/Standard Libraries/Basic Functions

rawset (table, index, value)table[index]value__newindextableindexnilvalue This function returns

2025-01-10 15:47:30
string.pack()
  • References/Lua/Lua/Standard Libraries/String Manipulation

string.pack (fmt, v1, v2, ···) Returns a binary string containing the values v1, v2, etc. packed (that is, serialized in binary form) according to the

2025-01-10 15:47:30
debug.getupvalue()
  • References/Lua/Lua/Standard Libraries/The Debug Library

debug.getupvalue (f, up) This function returns the name and the value of the upvalue with index up of the function f. The function returns nil

2025-01-10 15:47:30
file:close()
  • References/Lua/Lua/Standard Libraries/Input and Output Facilities

file:close () Closes file. Note that files are automatically closed when their handles are garbage collected, but that takes an unpredictable amount of time to happen

2025-01-10 15:47:30
table.sort()
  • References/Lua/Lua/Standard Libraries/Table Manipulation

table.sort (list [, comp]) Sorts list elements in a given order, in-place, from list[1] to list[#list]. If comp is given, then

2025-01-10 15:47:30
package.loadlib()
  • References/Lua/Lua/Standard Libraries/Modules

package.loadlib (libname, funcname) Dynamically links the host program with the C library libname. If funcname is "*", then it

2025-01-10 15:47:30
math.exp()
  • References/Lua/Lua/Standard Libraries/Mathematical Functions

math.exp (x) Returns the value ex (where e is the base of natural logarithms).

2025-01-10 15:47:30