[-n, +1, e]
void lua_concat (lua_State *L, int n);
Concatenates the n values at the top of the stack,
pops them, and leaves the result at the top.
If n is 1, the result is the single value on the stack
(that is, the function does nothing);
if n is 0, the result is the empty string.
Concatenation is performed following the usual semantics of Lua
(see §2.5.4). |