cygwin1.dll missing when compiling c++ with g++

I'm using cygwin and when I'm compiling hello world with gcc somehow the compiler doesn't understand about usi开发者_运维技巧ng std namespaces (some of them are missing), but when I compile with g++ yes they work. But when I click on the helloworld.exe it says that cygwin1.dll is missing.

Is there anything can I do?

"gcc" is the C compiler - and namespaces are not a part of the C language. "g++" is the C++ compiler, so it will understand namespaces.

Try the no-cygwin option when compiling to produce executables that depend on the mingw runtime instead of the cygwin runtime (which, AFAIR, introduces licencing issues).

cygwin1.dll errors could indicate a registry problem, a virus or malware.

Don't download cygwin1.dll. It can be an inappropriate version, or just unsafe. Try to reinstall cygwin (or try mingw32).