LuaJIT FFI string comparison

I'm binding a third-party C API that uses string statuses a lot. E.g. (pseudocode):

ffi.cdef [[
  struct Reply { char * str; size_t len };
  Reply * doSomething();
  void freeReply(Reply * p);

Most often str would be an "OK" string.

What is the fastest way to check that?

I would like to avoid string interning here:

local reply = ffi.gc(ffi.C.doSomething, ffi.C.freeReply)
assert(ffi.string(reply.str, reply.len) == "OK")


Not sure it is that much faster. What I would try is to call the strncmp from the standard C library.

Something like this:

ffi.cdef [[
  int strncmp ( const char * str1, const char * str2, size_t num );

local ok ="char[3]", "ok")

local reply = ffi.gc(ffi.C.doSomething, ffi.C.freeReply)
assert(ffi.C.strncmp(ok, reply.str, reply.len) == 0)

You may also try to first check that reply.len is 2 and then call memcmp instead of strncmp. It may be a little faster.

Need Your Help

Equality between a String value and an array value

java arrays string compare

So this is a portion of my code. If i entered " 1111 " for the preTranslation String, it should print out true but it prints out false. I'm guessing that .equal() cannot compare the two values but I

What is a good API to find the latitude and longitude of a zip code?

api geocoding latitude-longitude

Anyone know of a good free API to get the coordinates of a zip code? What I am currently using is

About UNIX Resources Network

Original, collect and organize Developers related documents, information and materials, contains jQuery, Html, CSS, MySQL, .NET, ASP.NET, SQL, objective-c, iPhone, Ruby on Rails, C, SQL Server, Ruby, Arrays, Regex, ASP.NET MVC, WPF, XML, Ajax, DataBase, and so on.