Lua and C + + Interactive learning Record VI: global function 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.c++ calling Lua in functions

Functions in the ①lua

1 function Add (x, y) 2     return x + y3End

②c++ calling function

1     //Lua->stack, global function position -12Lua_getglobal (L,"Add");3 4     //c->stack, passing in function arguments5Lua_pushinteger (L,Ten);6Lua_pushinteger (L, -);7 8     //Lua->stack, calling the function, 2 means passing in 2 arguments, 1 representing a return value, and putting the return value to the position of-19Lua_call (L,2,1);Ten  One     //stack->c Aprintf"Add function return value:%d\n", Lua_tointeger (L,-1));

2.Lua calling a function in C + +

C + + functions that can be called by ①lua must conform to the following function signatures:

typedef INT (*lua_cfunction) (lua_state *l);

In the function, the corresponding data is stack operation;

The return value represents the number of return values that are used by LUA in the stack.

Functions in ②c++

1 intAverage (lua_state*L) {2     //Lua->stack, get the number of Lua call function inputs3     intLua_args_count =lua_gettop (L);4 5     //lua->c, get the values of all the input parameters in Lua6Lua_number sum =0;7      for(inti =1; I <= Lua_args_count; ++i) {8Sum + =Lua_tonumber (L, i);9     }Ten  One     //C->stack, returns the mean and the total value back to the LUA ALua_pushnumber (L, Sum/lua_args_count); - lua_pushnumber (L, sum); -  the     //returns the number to Lua -     return 2; -}

③ registering C + + functions into Lua

1 " Average " , average); 2 3 /// /lua_register Macro replaces the following two functions 4 // lua_pushcfunction (L, average); 5 // Lua_setglobal (L, "average");

To invoke a function in C + + in ④lua

1 local ave,sum = average (ten,2)print("  ", Ave,"", sum)

Lua and C + + Interactive learning Record VI: global function interaction