Erlang购物计算：递归实现-优快云博客

本文链接：https://blog.youkuaiyun.com/zl8522115/article/details/7901013

本文介绍了一个使用Erlang实现购物计算的例子，通过递归处理商品列表达到总价计算。代码示例展示了如何处理包含不同商品数量的列表，并逐步解析递归过程。尽管Erlang的语法简洁，但递归逻辑可能对初学者来说较难理解。

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shop.erl

%% Author: Administrator
%% Created: 2012-8-23
%% Description: TODO: Add description to shop
-module(shop).
%%
%% Include files
%%

%%
%% Exported Functions
%%
-export([cost/1]).

%%
%% API Functions
%%
cost(oranges)
  ->5;
cost(newspaper)
  ->8;
cost(apples)
  ->2;
cost(pears)
  ->9;
cost(milk)
  ->7.


%%
%% Local Functions
%%

shop1.erl

%% Author: Administrator
%% Created: 2012-8-23
%% Description: TODO: Add description to shop1
-module(shop1).

%%
%% Include files
%%

%%
%% Exported Functions
%%
-export([total/1]).

%%
%% API Functions
%%
total([{What,N}|T])
  ->shop:cost(What)*N+total(T);
total([])
  ->0.


%%
%% Local Functions
%%

cd("/mnt/web/source_erlang/demo1/src").
c(shop).
c(shop1).
Buys=[{oranges,4},{newspaper,1},{apples,10},{pears,6},{milk,3}].
shop1:total(Buys).

这点代码很有意思,递归是必须的,主要是在shop:cost(What)*N+total(T)

T是列表的后面的数据,依次递归下去,直至为空,当为空时变成匹配total([])方法

执行方式应该是

oranges*4+{newspaper,1},{apples,10},{pears,6},{milk,3}=40+{newspaper,1},{apples,10},{pears,6},{milk,3}

40+newspaper*1=40+8+{apples,10},{pears,6},{milk,3}

一直下去,最后变成了

40+8+2*10+9*6+7*3+total([]) //total([])=0

ps:尼玛,这也太精简了,python哪能和这语言相比,不过就是真TMD难懂,递归精简,我擦了.

erlang 购物