timer:tc with argument

Given the following m开发者_高级运维odule:

run(N)-> timer:tc(?MODULE,fct,[N]).

I call it by run(100). from a shell and I have this:

{1, {'EXIT',{undef,[{parser,loop,"d"}, {timer,tc,3}, {erl_eval,do_apply,5}, {shell,exprs,7}, {shell,eval_exprs,7}, {shell,eval_loop,3}]}}}

100 is interpreted as a char ($d = 100) and not as an integer ! Where is my fault ?

In Erlang, [100] and "d" are indistinguishable, the code you show above isn't the problem. The Erlang shell is being helpful (for certain values of help) and printing [100] as "d" because it's a list containing only integers representing printable characters.

The real problem is the undef error in the above, my guess is that your parser module doesn't contain a function parser:loop/1 that you call via parser:fct/1.

Did you get any warnings on your compilation ? I suspect you will see at least one message about an unused function. As you are learning, if you see a warning message then investigate it, understand it and correct it. Generally speaking, you want your code to have no warning messages.

If a function is called in MFA style then it has to be exported in the source code. From what you've shown it's not clear if it is named "fct" or "loop". So, make sure your naming is consistent, and make sure it is exported : You need this in your source code (assuming the function is called "loop" and takes 1 argument) :

-export([loop/1]).

Error messages in Erlang can be tricky to decipher at first. Take some time to read more and become more familiar with them and you will save yourself lots of time going forward.