Re: Ask, how to implement the function like ipairs with C api?

[Jim Pryor <lists+lua@...>]

On Mon, Nov 02, 2009 at 03:54:20PM +0800, sagasw wrote:
>    I have a question when I read the manual.
>    lua_gettable could get table, and lua_getfield could get specific key.
> 
>    If I only know the table in top of stack like：
> 
>    local tbl_sample = {a = "aaa", b = "bbb", c= "ccc", 15}
> 
>    How could I get the information of table key-value pairs in c? And the
>    case is I don't know the key.
> 
>    Just like the function ipairs(), it doesn't need to know the key before
>    using the table.
> 
>    I read the source code of ipairs(), it says to use upvalue to aux the
>    function.
>    Who could give me c code sample for it?


Just call lua_next(L, index_of_table). It's in the Reference Manual.

If stack starts like this:
    -1: nil
    -2: your table

then after lua_next(L, -2), the stack will look like this:
    -1: "aaa"
    -2: "a"
    -3: your table

The Ref Manual has sample code for table traversals.

-- 
Profjim
profjim@jimpryor.net