Character Set and Source File Encoding

Character Set

In Erlang 4.8/OTP R5A the syntax of Erlang tokens was extended to allow the use of the full ISO-8859-1 (Latin-1) character set. This is noticeable in the following ways:

All the Latin-1 printable characters can be used and are shown without the escape backslash convention.

Atoms and variables can use all Latin-1 letters.

Octal Decimal Class 200 - 237 128 - 159 Control characters 240 - 277 160 - 191 - ¿ Punctuation characters 300 - 326 192 - 214 À - Ö Uppercase letters 327 215 × Punctuation character 330 - 336 216 - 222 Ø - Þ Uppercase letters 337 - 366 223 - 246 ß - ö Lowercase letters 367 247 ÷ Punctuation character 370 - 377 248 - 255 ø - ÿ Lowercase letters Character Classes.

In Erlang/OTP R16B the syntax of Erlang tokens was extended to handle Unicode. The support is limited to string literals and comments. Atoms, module names, and function names are restricted to the ISO-Latin-1 range. More about the usage of Unicode in Erlang source files can be found in STDLIB's User's Guide.

Source File Encoding

The Erlang source file encoding is selected by a comment in one of the first two lines of the source file. The first string that matches the regular expression coding\s*[:=]\s*([-a-zA-Z0-9])+ selects the encoding. If the matching string is not a valid encoding it is ignored. The valid encodings are Latin-1 and UTF-8 where the case of the characters can be chosen freely.

The following example selects UTF-8 as default encoding:

%% coding: utf-8

Two more examples, both selecting Latin-1 as default encoding:

%% For this file we have chosen encoding = Latin-1

%% -*- coding: latin-1 -*-

The default encoding for Erlang source files was changed from Latin-1 to UTF-8 in Erlang OTP 17.0.