Erlang Start![1]

练习链接： http://erlang.org/course/exercises.html

题目：

Simple sequential programs

1. Write functions temp:f2c(F) and temp:c2f(C) which convert between centigrade and Fahrenheit scales. (hint 5(F-32) = 9C)

2. Write a function temp:convert(Temperature) which combines the functionality of f2c and c2f. Example:

    > temp:convert({c,100}).
    => {f,212}
    > temp:convert({f,32}).
    => {c,0}

回答：

%% Author: Quon
%% Created: 2009-8-6
%%File: temp.erl
-module(temp).
-export([f2c/1,c2f/1,convert/1]).

%Ex1
f2c(F) ->
  (5*(F-32))/9.
  
c2f(C) ->
  9*C/5+32.

%Ex2
convert({c, C}) ->
  {f, 9*C/5+32};

convert({f, F}) ->
  {c, (5*(F-32))/9}.

更新：
发现一点小错误，默认的"/"操作符的结果是浮点数，如果需要输出整数，需要用div操作符，正确的结果为：

%% Author: Quon
%% Created: 2009-8-6
%%File: temp.erl
-module(temp).
-export([f2c/1,c2f/1,convert/1]).

%Ex1
f2c(F) ->
  (5*(F-32)) div 9.
  
c2f(C) ->
  9*C div 5+32.

%Ex2
convert({c, C}) ->
  {f, 9*C div 5+32};

convert({f, F}) ->
  {c, (5*(F-32)) div 9}.