定义新类型 [英] defining new types

问题描述

我确定这个答案相当简单......但我如何定义一个带范围检查的新

类型？


示例：我想定义一个类似于double的新类型，除了你

只能给它0.0到100.0之间的值。我也希望它尽可能地像一个

加倍，除了当它设置为无效数字的
时抛出异常。


想法？


谢谢，

Joe

I''m sure there''s a fairly easy answer for this... but how can I define a new
type with range checking?

Example: I want to define a new type that''s like a double, except that you
can only give it values from 0.0 to 100.0. I''d also like it to act like a
double as much as possible, except that an exception is thrown when it''s set
to an invalid number.

Ideas?

Thanks,
Joe

推荐答案

* Joe Laughlin：

* Joe Laughlin:

我确定这个答案相当简单......但我怎么能定义一个新的
示例：我想定义一个类似于double的新类型，除了你只能给它0.0到100.0之间的值。我也希望它尽可能地像双击一样，除了当它被设置为无效数字时抛出异常。

想法？

I''m sure there''s a fairly easy answer for this... but how can I define a new
type with range checking?

Example: I want to define a new type that''s like a double, except that you
can only give it values from 0.0 to 100.0. I''d also like it to act like a
double as much as possible, except that an exception is thrown when it''s set
to an invalid number.

Ideas?

原始C ++和C之间的区别在于C ++有类。


类是一种类型。


要定义新类型，请定义一个类。


提供您希望类型具有的操作。

给自己一本好的C ++书，比如说加速的C ++。


-

答：因为它弄乱了人们通常阅读文本的顺序。

问：为什么这么糟糕？

A：热门发布。

问：usenet和e-最令人烦恼的是什么？邮件？

The difference between original C++ and C was that C++ had classes.

A class is a type.

To define a new type, define a class.

Supply the operations you want the type to have.

Get yourself a good C++ book, e.g. "Accelerated C++".

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

Joe Laughlin写道：

Joe Laughlin wrote:

我确定这个答案相当简单......但我怎么能用范围检查定义一个新的
类型？

示例：我想定义一个类似于double的新类型，除了你只能从它给它的值0.0到100.0。我也希望它尽可能地像双击一样，除了当它被设置为无效数字时抛出异常。

想法？

I''m sure there''s a fairly easy answer for this... but how can I define a new
type with range checking?

Example: I want to define a new type that''s like a double, except that you
can only give it values from 0.0 to 100.0. I''d also like it to act like a
double as much as possible, except that an exception is thrown when it''s set
to an invalid number.

Ideas?

这个google群组链接指向最近关于comp.std.c ++的讨论。

http://tinyurl.com/6zyg9

Joe Laughlin发布：

Joe Laughlin posted:

我确定这个答案相当简单......但是如何定义一个带范围检查的新类型？

示例：我想定义一个类似于double的新类型，除了
你只能给它0.0到100.0之间的值。我也希望它尽可能地像双倍一样行动，除非当它被设置为无效数字时会抛出异常


想法？

谢谢，
Joe

I''m sure there''s a fairly easy answer for this... but how can I define
a new type with range checking?

Example: I want to define a new type that''s like a double, except that
you can only give it values from 0.0 to 100.0. I''d also like it to act
like a double as much as possible, except that an exception is thrown
when it''s set to an invalid number.

Ideas?

Thanks,
Joe

用你的大脑：


class RestrictiveDouble
{

public：class bad_proposal {};


private：


双数据;


Set（建议使用双const）

{

if（建议> 100 ||建议< 0）抛出bad_proposal ;


数据=建议;

}


公开：


RestrictiveDouble& operator =（建议双const）

{

套装（建议）;

}


//复制构造函数是不必要的


//在这里放置一个构造函数


//在这里放一个运算符

};


我会为你完成它，但是一半之后我认为它可能会为你做好功课。


-JKop

Use your brain:

class RestrictiveDouble
{
public: class bad_proposal {};

private:

double data;

Set(double const proposed)
{
if (propose > 100 || proposed < 0) throw bad_proposal;

data = proposed;
}

public:

RestrictiveDouble& operator=(double const proposed)
{
Set(proposed);
}

//Copy constructor is unnecessary

//Put a constructor here

//Put an operator double here
};

I would''ve finished it for you, but then half way through I thought it may
have been homework for you.

-JKop

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