Function lua_tointegerx 

pub unsafe extern "C-unwind" fn lua_tointegerx(
    L: *mut lua_State,
    idx: c_int,
    isnum: *mut c_int,
) -> lua_Integer

Attempts to convert the value at the given index to an integer.

This function operates similarly to lua_tonumberx, but adds the step of flooring the result to an integer. While a string may be turned into a number on the stack, the value on the stack will not be floored to an integer.