what does '...' mean in c/c++?

[Damian]

Recently i view nginx source code, and see the code below:

switch (rc) {
case NGX_HTTP_SPECIAL_RESPONSE ... NGX_HTTP_INTERNAL_SERVER_ERROR:
ngx_http_finalize_request(r, rc);
break;
default:

what does ... mean in case statement?
confusing...

[LB]

It is a compiler extension, not part of C or C++ standard:
http://ideone.com/qTEofj
http://coliru.stacked-crooked.com/a/6d458bdb3096cd06

clang wrote:

main.cpp:10:11: warning: use of GNU case range extension [-Wgnu-case-range]
                        case 1 ... 100: std::cout << "a"; break;
                               ^

[Little Bobby Tables]

LB is correct OP, however just so you are aware, the ellipsis operator (...) does have a standardized use which can be seen at:
http://www.cplusplus.com/articles/EhvU7k9E/