lua_touserdata[-0, +0, –] void *lua_touserdata (lua_State *L, int index); If the value at the given index is a full userdata, returns its block address. If the value is a light userdata, returns its pointer. Otherwise, returns NULL.

lua_tothread[-0, +0, –] lua_State *lua_tothread (lua_State *L, int index); Converts the value at the given index to a Lua thread (represented as lua_State*). This value must be a thread; otherwise, the function returns NULL.

lua_tostring[-0, +0, m] const char *lua_tostring (lua_State *L, int index); Equivalent to lua_tolstring with len equal to NULL.

lua_topointer[-0, +0, –] const void *lua_topointer (lua_State *L, int index); Converts the value at the given index to a generic C pointer (void*). The value can be a userdata, a table, a thread, or a function; otherwise, lua_topointer returns NULL. Different objects will give different pointers. There is no way to convert the pointer back to its original value. Typically this function is used only for hashing and debug information.

lua_tonumberx[-0, +0, –] lua_Number lua_tonumberx (lua_State *L, int index, int *isnum); Converts the Lua value at the given index to the C type lua_Number (see lua_Number). The Lua value must be a number or a string convertible to a number (see §3.4.3); otherwise, lua_tonumberx returns 0. If isnum is not NULL, its referent is assigned a boolean value that indicates whether the operation succeeded.

lua_tonumber[-0, +0, –] lua_Number lua_tonumber (lua_State *L, int index); Equivalent to lua_tonumberx with isnum equal to NULL.

lua_tolstring[-0, +0, m] const char *lua_tolstring (lua_State *L, int index, size_t *len); Converts the Lua value at the given index to a C string. If len is not NULL, it sets *len with the string length. The Lua value must be a string or a number; otherwise, the function returns NULL. If the value is a number, then lua_tolstring also changes the actual value in the stack to a string. (This change confuses lua_next when lua_tolstring is applied to keys during a table traversal.) lua_tolstr

lua_tointegerx[-0, +0, –] lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum); Converts the Lua value at the given index to the signed integral type lua_Integer. The Lua value must be an integer, or a number or string convertible to an integer (see §3.4.3); otherwise, lua_tointegerx returns 0. If isnum is not NULL, its referent is assigned a boolean value that indicates whether the operation succeeded.

lua_tointeger[-0, +0, –] lua_Integer lua_tointeger (lua_State *L, int index); Equivalent to lua_tointegerx with isnum equal to NULL.

lua_tocfunction[-0, +0, –] lua_CFunction lua_tocfunction (lua_State *L, int index); Converts a value at the given index to a C function. That value must be a C function; otherwise, returns NULL.