how to get string insted of char pointer in Lua

Question

I have a big problem....can't solve it. I have free pascal program and lua script.

function getString(i:integer):PChar;public; stdcall;
begin
//something to do 
Result:=strnew(PChar('newString'));
end

by passing the registration functions there is Lua implementation

ffi.cdef
[[
char*__stdcall getString(i:integer);
]]
local str =ffi.C.getString(5)
print (tostring(str))

instead of 'newString' I get address of cdata. Please anybody help me to understand this moment. How to solve it?

David Heffernan · Accepted Answer · 2016-09-28 07:28:29Z

2

tostring is being passed an address, and so gives you the string representation of that address. You need ffi.string instead.

local str = ffi.string(ffi.C.getString(5))

Now str is a Lua string containing what was returned by your Pascal code.

Your other perhaps bigger problem is surely that you are allocating a string on the Pascal module's heap with no obvious way of deallocating it.

answered Sep 28, 2016 at 7:28

David Heffernan

616k46 gold badges1.1k silver badges1.5k bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

David Heffernan Over a year ago

Note: I know nothing of Lua and based my answer on its documentation and this answer: stackoverflow.com/questions/25597155/… So there may be syntax inaccuracies. I'm sure you know Lua so will be able to cope.

David Heffernan Over a year ago

How about some detail as to what does happen. Could perfectly well be a defect in your Pascal code.

Lua Jit Over a year ago

Thanks, Everything is ok ! It was other mistake ))))) Thank you

David Heffernan Over a year ago

Good. Glad I wasn't going mad.

Collectives™ on Stack Overflow

how to get string insted of char pointer in Lua

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related