luaL_dostring什么都不放在堆栈？ [英] luaL_dostring puts nothing on the stack?

问题描述

我试图学习使用C ++连接Lua的基础知识，但我遇到了一个问题。
我想调用一个函数返回一个字符串，然后使用C ++端的字符串，但luaL_dostring似乎没有放在Lua堆栈。

I'm trying to learn the basics of interfacing Lua with C++, but I've run into a problem. I want to call a function that returns a string, and then work with the string on the C++ side, but luaL_dostring seems to put nothing on the Lua stack.

即使一个简单的测试似乎不能正常工作：

Even a simple test doesn't seem to work properly:

lua_State* lua = lua_open();
luaL_openlibs(lua);

//Test dostring.
luaL_dostring(lua, "return 'derp'");

int top = lua_gettop(lua);
cout << "stack top is " <<top << endl;

//Next, test pushstring.
lua_pushstring(lua, "derp");

top = lua_gettop(lua);
cout << "stack top is " << top << endl;

输出：

stack top is 0
stack top is 1

任何想法？ / p>

Any ideas?

推荐答案

Aha，发现了问题。根据此页面，在Lua 5.1中，luaL_dostring忽略返回。

Aha, found the problem. According to this page, in Lua 5.1 luaL_dostring ignores returns. The code I had would probably work in Lua 5.2.

要改变功能，你应该使用：

To alter the functionality, you should use:

#undef luaL_dostring
#define luaL_dostring(L,s)  \
    (luaL_loadstring(L, s) || lua_pcall(L, 0, LUA_MULTRET, 0))

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