# Binary String pattern matching

Harenson Henao harenson@REDACTED
Wed Dec 9 19:58:07 CET 2020

```You may want to move the currency to the front of the bitstring and then
pattern match it like: currency_to_credits({cur, <<"EUR", Amount/binary>>},
Acc) ...

On Wed, Dec 9, 2020 at 1:49 PM Java House <java4dev@REDACTED> wrote:

> there is a typo in the example
> currrency_to_credits({cur, << Value , "CHF">>}, Acc)
>   when Value >= <<"1000">>, Value =< <<"10000">> ->
>      {chf, Acc + Value };
> currrency_to_credits({cur, << Value , "EUR">>}, Acc)
>   when Value >= <<"1000">>, Value =< <<"10000">> ->
>      {eur, Acc + Value };
> currrency_to_credits({cur, << Value , "US">>}, Acc)
>   when Value >= <<"1000">>, Value =< <<"10000">> ->
>      {us, Acc + Value };
>
> Στις Τετ, 9 Δεκ 2020 στις 7:17 μ.μ., ο/η Java House <java4dev@REDACTED>
> έγραψε:
>
>> Hello all
>>
>> I am learning Erlang and have stuck to the following problem.
>> How to write a function with pattern matching when the parameter is a
>> binary string.
>>
>> I have a list of binary strings e.g.
>> <<3123CHF>>
>> <<341424343EUR>>
>> <<14143US>>
>>
>> I am trying to create a function that matches according to a pattern.
>>
>> currrency_to_credits({cur, <<A, "CHF">>}, Acc)
>>   when Value >= <<"1000">>, Value =< <<"10000">> ->
>>      {chf, Acc + A};
>> currrency_to_credits({cur, <<A, "EUR">>}, Acc)
>>   when Value >= <<"1000">>, Value =< <<"10000">> ->
>>      {eur, Acc + A};
>> currrency_to_credits({cur, <<A, "US">>}, Acc)
>>   when Value >= <<"1000">>, Value =< <<"10000">> ->
>>      {us, Acc + A};
>>
>> But this does not seem to be the right way.
>> How can I create a pattern for binary string?
>> will it work better for list string? How?
>>
>> Thank you
>> Nikolas
>>
>
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