perl 的eval中，不应当使用 next

The next command is like the continue statement in C; it starts the next iteration of the loop:

LINE: while (<STDIN>) {

next LINE if /^#/; # discard comments

#...

}

Note that if there were a continue block on the above, it would get executed even on discarded lines. If the LABEL is omitted, the command refers to the innermost enclosing loop.

next cannot be used to exit a block which returns a value such as eval {} , sub {} or do {} , and should not be used to exit a grep() or map() operation.

Note that a block by itself is semantically identical to a loop that executes once. Thus next will exit such a block early.