c/c++ linux programming by examples my programming tips and techniques

Calling Lua function from c++ is very simple. Value passing between c++ and Lua goes through stack, Lua C API provides a convenience ways for you to call Lua function from C. To call Lua function, you need to specify:

1. Function Name.
2. Parameters of function call.
3. Return values expected ( Lua function support multiple results reture)

Let say my lua function name call f in last.lua, takes 2 parameters.

-- last.lua
function f (x, y)
    return (x^2 * math.sin(y))/(1 - x)
end

I perform function call from c++ like this:

Compile it with g++ like this:

g++ -o last{,.cc} -llua -ldl

The results:

Result: -12.158958

Brief explanation of the C++ codes above:
First, I trigger lua_getglobal to get the function name, then I push 2 parameters to stack. I make lua_pcall by telling Lua I have 2 params and expect 1 value return. Upon success, I retrieve the return value from the top of the stack.