Lua and C + + Interactive learning record five: global array interaction

The main content is reproduced from: Zilong People Blog (strongly recommended to go to the sub-Longshan blog completely learn it again)

Part of the content is read from: "Lua 5.3 Reference Manual," the Chinese version of the translator Cloud wind production KAVCC

vs2013+lua-5.3.3

1. Arrays

The ① array is a table with a key value starting at 1 and incrementing continuously.

The ② index number is starting from 1, not starting from 0.

2. Since it is a table, it is of course possible to read and write with the contents of the previous section.

LUA also provides some APIs that operate on arrays only, as follows:

①lualib_api Lua_integer (Lual_len) (lua_state *l, int idx);

The number of array elements can be obtained by using the array.

Returns the "Length" of the value at a given index as a number, which is equivalent to invoking the ' # ' operation in Lua. (Non-array use # will not get the correct value)

If the action result is not an integer, an error is thrown. (This happens only when the triggering meta-method is used.) ）

②lua_api Int (Lua_rawgeti) (lua_state *l, int idx, Lua_integer n);

Note the corresponding Lua_rawget function.

Gets the array value of index number n, which returns an int value of the type of the value.

This is a direct access that does not trigger a meta-method and is highly efficient.

③lua_api void (Lua_rawseti) (lua_state *l, int idx, Lua_integer n);

Note the corresponding Lua_rawset function

Sets the array value of index number n.

This function pops the value out of the stack. The assignment is straightforward, i.e. it does not trigger a meta-method and is highly efficient.

3.c++ reading an array in Lua

Array in ①lua

Global_c_read_array = {5,6.78,"array string"}

Read in ②c++

1 //Lua->stack, get global array, position -12Lua_getglobal (L,"Global_c_read_array");3 4     //get the array length5Lua_integer Array_len = Lual_len (L,-1); 6      for(Lua_integer i =1; I <= Array_len; ++i) {7         //lua->stack, global array position-1, then I is the corresponding index value, put the return value to the position of-18         intRet_type = Lua_rawgeti (L,-1, i);9 Ten         //--------------The original operation table function that was substituted------------- One         //Lua_pushinteger (L, i); A         //int ret_type = lua_gettable (L,-2);//you can also use int ret_type = Lua_rawget (L,-2);  -  -         //stack->c the         if(Ret_type = =Lua_tnumber) { -             if(Lua_isinteger (L,-1)){ -printf"%lld\n", Lua_tointeger (L,-1)); -             } +             Else if(Lua_isnumber (L,-1)){ -printf"%g\n", Lua_tonumber (L,-1)); +             } A         } at         Else if(Ret_type = =lua_tstring) { -printf"%s\n", Lua_tostring (L,-1)); -         } -  -Lua_pop (L,1); -}

4.c++ writing to LUA arrays

①c++ Write

1 //C->stack, create a new table and put it in the position of-12 lua_newtable (L);3 4     //c->stack, create the corresponding Key-val5Lua_pushinteger (L,7);//Setting the value6Lua_rawseti (L,-2,1);//Correspondence Key-val7 8Lua_pushnumber (L,8.9);//Setting the value9Lua_rawseti (L,-2,2);//Correspondence Key-valTen  OneLua_pushstring (L,"test_string");//Setting the value ALua_rawseti (L,-2,3);//Correspondence Key-val -  -     //--------------The original operation table function that was substituted------------- the     //Lua_pushinteger (L, 1);//Set Key -     //Lua_pushinteger (L, 7);//Setting the value -     //lua_settable (L,-3);//You can also use Lua_rawset (l,-3); -  +     //Lua_pushinteger (L, 2);//Set Key -     //Lua_pushnumber (L, 8.9);//Setting the value +     //lua_settable (L,-3);//You can also use Lua_rawset (l,-3); A  at     //Lua_pushinteger (L, 3);//Set Key -     //lua_pushstring (L, "test_string");//Setting the value -     //lua_settable (L,-3);//You can also use Lua_rawset (l,-3); -  -      -     //Stack->lua, assigns the array to Lua, and pops the array inLua_setglobal (L,"Global_c_write_array");

② Lua reads in the Hello.lua file

1 if  Then 2      for 1  Do 3         Print ("", Global_c_write_array[i]) 4     End 5 End

Lua and C + + Interactive learning record five: global array interaction