by Example

Constants


Constants in Erlang can be created through the use of macros.




You can define macros for variables or even functions




To expand a macro in your code, use the "?" symbol
followed by the macro name.





-module(constants).
-compile(export_all).


-define(N, 123).
-define(M, "what").
-define(SQUARED (X), X*X).



showConstants() ->
    io:format("N = ~p ~n", [?N]),
    io:format("M = ~p ~n", [?M]),
    io:format("~p ~n", [?SQUARED(5)]).
N = 123
M = "what"
25


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