输出ETS表Erlang的内容

Question

I am new to the world of Erlang so I am trying to experiment with it.

I have an ETS table that is called numbers.

ets:new(numbers,[ordered_set,named_table])

It has the format [{Name,Number},{Name,Number}] etc.

I am wondering is there a way to output the contents of the whole the ets table?

Answer 1

Tl;dr

you can use

ets:match_object(Tab, {'$0', '$1'}).

Where Tab is your table name, ie numbers .

In depth:

The second argument is a match pattern , leaving "free variables" '$0' and '$1' .

Let's say you inserted:

> ets:insert(Tab, [{age, 45}, {length, 10}, {height, 45}]). 

You could get out all {_, 45} tuples with:

> ets:match_object(Tab, {'$0', 45}). 
[{age, 45}, {height, 45}]

By making all (in this case, 2) of the tuple parameters free variables, you will match everything in the table.

I highly recommend reading Learn You Some Erlang for more info!