简单的铸造问题 [英] Simple Casting Question

问题描述

大家好，

我有PRECISION在预处理器代码中定义了

，它可以是int，float或double，但我不知道

代码是什么。

现在，如果我想将零分配给PRECISION变量，

以下哪一行是正确的：

PRECISION myVar =（PRECISION）0; / *一个* /


PRECISION myVar =（PRECISION）0.0; / *两个* /


PRECISION myVar = 0; / *三* /


PRECISION myVar = 0.0; / *四* /


提前谢谢，

Alex

解决方案

< blockquote> 5月18日，下午7:35，alex.j ... @ gmail.com写道：

大家好，


我有PRECISION在预处理器代码中定义了

，它可以是int，float或double，但我不知道

代码是什么。

现在，如果我想将零分配给PRECISION变量，

以下哪一行是正确的：


PRECISION myVar =（PRECISION）0; / *一个* /


PRECISION myVar =（PRECISION）0.0; / *两个* /


PRECISION myVar = 0; / *三* /


PRECISION myVar = 0.0; / *四* /


提前谢谢，

Alex

你可以试试不同的组合，看看哪个给你一个

错误，哪个正常。例如，假设PRECISION是一个浮动：

1）浮动myVar =（float）0; / * cast不需要，编译器会自动执行
* /

2）float myVar =（float）0.0; / * 0.0默认为加倍，施放没有

受伤* /

3）浮动myVar = 0; / *编译器自己执行强制转换* /

4）float myVar = 0.0; / * 0.0默认为double，但这是

okay * /


现在，假设PRECISION是一个整数类型，例如int：

1）int myVar =（int）0; / *浪费打字时间* /

2）int myvar =（int）0.0; / *编译器可以在编译时执行此操作

时间，但不好主意* /

3）int myVar = 0; / *这就是我们通常的做法* /

4）int myVar = 0.0; / *那个是编译器错误* /


所以方法4有问题，方法3打字最少，方法1

和2也没关系。


自己尝试一下，我希望我没错。


- Marty Wolfe


非常简单。这是方法三。 - 阿尔弗雷德·希区柯克（Alfred Hitchcock），三个人的方式来抢劫银行

al ******* @ gmail.com 写道：

Hello all，


我有PRECISION在预处理器代码中定义了

，它可以是int，float或double，但我不知道

代码是什么。

现在，如果我想将零分配给PRECISION变量，

以下哪一行是正确的：


PRECISION myVar =（PRECISION）0; / *一个* /


PRECISION myVar =（PRECISION）0.0; / *两个* /


PRECISION myVar = 0; / *三* /


PRECISION myVar = 0.0; / *四* /

我喜欢/ *三* /。


-

pete

al*******@gmail.com 写道：

我有PRECISION在预处理器代码中定义了

，它可以是int，float或double，但我不知道

代码是什么。

现在，如果我想将零分配给PRECISION变量，

以下哪一行是正确的：


PRECISION myVar =（PRECISION）0; / *一个* /


PRECISION myVar =（PRECISION）0.0; / *两个* /


PRECISION myVar = 0; / *三* /


PRECISION myVar = 0.0; / *四* /

所有四个都是正确的。第三种是首选，恕我直言。


PRECISION可以是整数类型还是

浮点类型似乎很奇怪。整数和浮点类型的行为方式非常不同，有时甚至是完全不同的方式。我认为

编写的代码不知道它是否处理整数

或浮点值会很困难且容易出错。 br />

-

Keith Thompson（The_Other_Keith） ks *** @ mib。组织< http://www.ghoti.net/~kst>

诺基亚

我们必须做点什么。这是事情。因此，我们必须这样做。

- Antony Jay和Jonathan Lynn，是部长

Hello all,
I have "PRECISION" defined in the preprocessor code
and it could be int, float or double, but I do not know in the
code what it is.

Now if I want to assign zero to a "PRECISION" variable,
which of the following lines are correct:
PRECISION myVar = (PRECISION) 0; /* One */

PRECISION myVar = (PRECISION) 0.0; /* Two */

PRECISION myVar = 0; /* Three */

PRECISION myVar = 0.0; /* Four */

Thank you in advance,
Alex

解决方案

On May 18, 7:35 pm, [e-mail] wrote:

Hello all,

I have "PRECISION" defined in the preprocessor code
and it could be int, float or double, but I do not know in the
code what it is.

Now if I want to assign zero to a "PRECISION" variable,
which of the following lines are correct:

PRECISION myVar = (PRECISION) 0; /* One */

PRECISION myVar = (PRECISION) 0.0; /* Two */

PRECISION myVar = 0; /* Three */

PRECISION myVar = 0.0; /* Four */

Thank you in advance,
Alex

You could try the different combinations and see which gives you an
error, and which works properly. For example, assuming PRECISION is a
float:
1) float myVar = (float) 0; /* cast not needed, the compiler does
it automatically */
2) float myVar = (float) 0.0; /* 0.0 defaults to double, cast doesn''t
hurt */
3) float myVar = 0; /* Compiler performs cast on its own */
4) float myVar = 0.0; /* 0.0 defaults to double, but this is
okay */

Now, assuming PRECISION is an integral type, such as int:
1) int myVar = (int) 0; /* A waste of typing time */
2) int myvar = (int) 0.0; /* The compiler can do this at compile
time, but bad idea */
3) int myVar = 0; /* That''s how we usually do it */
4) int myVar = 0.0; /* That one is a compiler error */

So method 4 is problematic, method 3 is the least typing, methods 1
and 2 are okay too.

Try this on your own, I hope I''m not wrong.

-- Marty Wolfe

"Very simple. This is method three." -- Alfred Hitchcock, "Three
Ways to Rob a Bank"

al*******@gmail.com wrote:

Hello all,
I have "PRECISION" defined in the preprocessor code
and it could be int, float or double, but I do not know in the
code what it is.

Now if I want to assign zero to a "PRECISION" variable,
which of the following lines are correct:
PRECISION myVar = (PRECISION) 0; /* One */

PRECISION myVar = (PRECISION) 0.0; /* Two */

PRECISION myVar = 0; /* Three */

PRECISION myVar = 0.0; /* Four */

I like /* Three */.

--
pete

al*******@gmail.com writes:

I have "PRECISION" defined in the preprocessor code
and it could be int, float or double, but I do not know in the
code what it is.

Now if I want to assign zero to a "PRECISION" variable,
which of the following lines are correct:
PRECISION myVar = (PRECISION) 0; /* One */

PRECISION myVar = (PRECISION) 0.0; /* Two */

PRECISION myVar = 0; /* Three */

PRECISION myVar = 0.0; /* Four */

All four are correct. The third is preferred, IMHO.

It does seem odd that PRECISION can be either an integer type or a
floating-point type. Integer and floating-point types behave in very
different, and sometimes quite subly different, ways. I would think
that writing code that doesn''t know whether it''s dealing with integers
or floating-point values would be difficult and error-prone.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

这篇关于简单的铸造问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！