Interaction between C language and Lua (practice 2)

C Language and Lua Interaction （ Practice two ）

How to build the environment can be referred to ：https://blog.csdn.net/qq135595696/article/details/125137333?spm=1001.2014.3001.5501

C Language call Lua function

   stay lua.c Medium main Function , Delete existing code , Change to the following code ：

void test2(lua_State* L)
{
    
	// Get how many elements already exist in the stack 
	int top = lua_gettop(L);
	printf("top:[%d]\n", top);

	// Name the global variable func2 Function stack of , Returns the type of the value 
	int type = lua_getglobal(L, "func2");
	//printf("type:%d\n", type);

	// Call the function in protected mode , After calling, you must restore Lua Stack , For example, after calling a function, it returns two values , You have to use lua_pop(L,2) take Lua Stack empty .
	// When the function is called , All the parameters and the function itself will be out of the stack , The return value of the function is pushed onto the stack .
	//int lua_pcall(lua_State* L,int nergs,int nresults,int msgh);
	//L：Lua virtual machine 
	//nergs： The number of formal parameters pushed into the stack 
	//nresults： Number of returned parameters 
	//msgh If 0, The error message returned to the top of the stack is exactly the same as the original message .


	// Press in a string 
	lua_pushstring(L, "Hello Wolrd");
	// Press in an integer 
	lua_pushnumber(L, 1000);
	// Push in a boolean type 
	lua_pushboolean(L, 666);
	// Call function 
	if (0 != lua_pcall(L, 3, 2, 0))
		printf("error[%s]\n", lua_tostring(L, -1));
	printf("%d=====\n", lua_gettop(L));
	const char* str = lua_tostring(L, -2);// Get the returned value 
	int value = lua_tonumber(L, -1);//-1 Represents the top of the stack (-2 Under the top of the stack ),1 Indicates the bottom of the stack 
	printf(" To the top of the stack ：%d  Under the top of the stack ：%s\n", value, str);

	// Clear the return value , Stack balancing 
	lua_pop(L, lua_gettop(L) - top);// perhaps , Since you already know that calling this function returns two parameters , You can use it directly lua_pop(L, 2);
	top = lua_gettop(L);
	printf("top:[%d]\n", top);
	printf("---- Demarcation line ---\n");
}

int main(int argc, char** argv) {
    
	//  Create a virtual machine 
	lua_State* L = luaL_newstate();
	//  Load some common system libraries 
	luaL_openlibs(L);

	if (luaL_dofile(L, "main.lua"))
		printf("%s\n", lua_tostring(L, -1));
    
	test2(L);
	test2(L);
	test2(L);
	test2(L);
    
	//  Shut down the virtual machine 
	lua_close(L);
	return 0;
}

   among ,main.lua The code for is as follows （ Pay attention to the need to follow lua.c Files are placed in the same file path ）：

-- main.lua
function func2(a,b,c)
  print(a,b,c)
	return "hello world",123
end

   The operation results are as follows ：

C Set a language table Data to Lua

Example 1

   stay lua.c Medium main Function , Delete existing code , Change to the following code ：

int main(int argc, char** argv) {
    
	//  Create a virtual machine 
	lua_State* L = luaL_newstate();
	//  Load some common system libraries 
	luaL_openlibs(L);

	lua_newtable(L);// Create a table type 
	lua_pushstring(L, "dlw");// Now there are two elements in the stack ,table and “dlw”
	int top = lua_gettop(L);
	printf("top:%d\n", top);
	lua_pushstring(L, "111");// Now there are three elements in the stack ,“111” Stack top ,“dlw” Under the top of the stack 
	top = lua_gettop(L);
	printf("top:%d\n", top);
	lua_settable(L, -3);// In the stack key and value Set to table In the middle , by {"dlw" = "111"}, At the moment, there is only table
	top = lua_gettop(L);
	printf("top:%d\n", top);

	lua_setglobal(L, "tab"); // Will now create table Name it  tab Global variables , Now the stack is empty 
	top = lua_gettop(L);
	printf("top:%d\n", top);


	lua_newtable(L);
	lua_pushstring(L, "dlw");// Now there are two elements in the stack 
	top = lua_gettop(L);
	printf("top:%d\n", top);
	lua_setfield(L, 1, "name");// perhaps lua_setfield(L, -2, "name"); Now there is an element in the stack , Means to insert... Under the top of the stack “name”, here {"name"="dlw"}, Press it in again table in 
	top = lua_gettop(L);
	printf("top:%d\n", top);
	lua_setglobal(L, "tab1");

	//  load lua Document and execute   The name is  main.lua
	if (luaL_dofile(L, "main.lua"))
	{
    
		//  stay lua in  -1 Represents the top of the stack   If something goes wrong   The error result will be placed at the top of the stack 
		printf("%s\n", lua_tostring(L, -1));
	}
	//  Shut down the virtual machine 
	lua_close(L);
	return 0;
}

   among ,main.lua The code for is as follows （ Pay attention to the need to follow lua.c Files are placed in the same file path ）：

-- main.lua
print(tab.dlw)
print(tab1.name)

   The operation results are as follows ：

Example 2

int main(int argc, char** argv) {
    
	//  Create a virtual machine 
	lua_State* L = luaL_newstate();
	//  Load some common system libraries 
	luaL_openlibs(L);
    
	// Create a table
	lua_newtable(L);
	
	lua_pushstring(L, "dlw");
	// Make an equivalent of  table["name"] = "dlw" The operation of , here "name" Is the value at the given index , and "dlw" Is the value at the top of the stack 
	lua_setfield(L, 1, "name");

	lua_pushstring(L, "Hello World");
	lua_rawseti(L, -2, 1);// Associate the element at the specified index position with the top of the stack element , namely table[1] = "Hello World";

	lua_setglobal(L, "tab");// Will now create table Name it tab Global variables 


	//  load lua Document and execute   The name is  main.lua
	if (luaL_dofile(L, "main.lua"))
	{
    
		//  stay lua in  -1 Represents the top of the stack   If something goes wrong   The error result will be placed at the top of the stack 
		printf("%s\n", lua_tostring(L, -1));
	}
    
	//  Shut down the virtual machine 
	lua_close(L);
	return 0;
}

-- main.lua
print(tab.name)
print(tab[1])

   The operation results are as follows ：

C Language call Lua Set up table type

   stay lua.c Medium main Function , Delete existing code , Change to the following code ：

int main(int argc, char** argv) {
    
	//  Create a virtual machine 
	lua_State* L = luaL_newstate();
	//  Load some common system libraries 
	luaL_openlibs(L);

	//  load lua Document and execute   The name is  main.lua
	if (luaL_dofile(L, "main.lua"))
	{
    
		//  stay lua in  -1 Represents the top of the stack   If something goes wrong   The error result will be placed at the top of the stack 
		printf("%s\n", lua_tostring(L, -1));
	}
	int top = lua_gettop(L);
	printf("%d\n", top);

	lua_getglobal(L, "tab");// Get global variables tab
	top = lua_gettop(L);
	printf("%d\n", top);
	// Data type checking , Check whether it is a table .
	luaL_checktype(L, -1, LUA_TTABLE);// At this point, the stack is still an element 

	top = lua_gettop(L);
	//printf("%d\n", top);

	// take key Pressure into the stack , Function will return value Value to the top of the stack 
	if (LUA_TSTRING == lua_getfield(L, -1, "name"))// Determine if it's a string 
	{
    
		top = lua_gettop(L);
		printf("%d\n", top);
		const char* str = luaL_checkstring(L, -1);
		printf("%s\n", str);
	}

	lua_pop(L, 1);// Balance the stack 

	// take key Pressure into the stack , Function will return value Value to the top of the stack 
	if (LUA_TSTRING == lua_geti(L, -1, 2))
	{
    
		const char* str = luaL_checkstring(L, -1);
		printf("%s\n", str);
	}

	lua_pop(L, 1);//  Balance the stack 

	lua_pop(L, 1);//  Balance the stack , This is the lua_getglobal(L, "tab") Balance 
    
	//  Shut down the virtual machine 
	lua_close(L);
	return 0;
}

   among ,main.lua The code for is as follows （ Pay attention to the need to follow lua.c Files are placed in the same file path ）：

-- main.lua
tab = {
    name = 'dlw'}
tab[1] = 123321
tab[2] = '123321aa'

   The operation results are as follows ：