what is this compile error , my code compiles fine in debug mode but not release mode

Linking...
libcp.lib(locale.obj) : error LNK2001: unresolved external symbol ___security_cookie
libcp.lib(wlocale.obj) : error LNK2001: unresolved external symbol ___security_cookie
libcp.lib(xlocale.obj) : error LNK2001: unresolved external symbol ___security_cookie
libcp.lib(locale.obj) : error LNK2001: unresolved external symbol @__security_check_cookie@4
libcp.lib(wlocale.obj) : error LNK2001: unresolved external symbol @__security_check_cookie@4
libcp.lib(xlocale.obj) : error LNK2001: unresolved external symbol @__security_check_cookie@4
Release/VNC Connecter.exe : fatal error LNK1120: 2 unresolved externals

It's not a compile error, it's a linker error. Check your linker settings on release as compared to debug

and what settings am i looking for exactly

What libraries and files are being included for each mode (debug and release). And I don't mean #include.

It might be in Project Options -> Linker Options or something.

Anyway, be rest assured that it is not your code -- just the libraries you're linking it to.