Check the socket descriptor.
Check the socket descriptor.
- Attention
- None
- Parameters
-
| nfds | [IN] Total number of file descriptors that are listened on |
| readfds | [IN] Readable file descriptor (optional) |
| writefds | [IN] Descriptor of a writable file. This parameter is optional. |
| exceptfds | [IN] Exception file descriptor (optional) |
| timeout | [IN] Set the timeout interval. |
- Return values
-
| If | the operation succeeds, Number of ready descriptors are returned; |
| If | the operation fails, a negative value is returned; |
| If | the operation times out, 0 is returned |