meaning of this expression extern __shared__ float shared[];


can anybody tell me the meaning of the following expression:

extern __shared__ float shared[];

(I understand that we use 'extern C " when we are compiling a C++ code using a non C++ compiler, but here the meaning is not clear)

Thanks in advance

It means the shared memory used by shared with be allocated at run time during kernel invocation. Described in detail in section B.2.3 of the programming guide. You might want to read it.