什么与cmath的四舍五入？！ [英] What's up with rounding in cmath?!
问题描述
我无法编译以下行。
int a = round（2.6）;
当然，我有包括< cmathand我可以去地板和
天花板没有问题。然而，四舍五入似乎并没有完全发挥作用。编译器咆哮说：
错误3错误C3861：''round''：找不到标识符
这是'这个故事的结尾。我可以（并且很可能是
）只需添加0.5和地板 - 如果结果但是
那是'错了，所以错了......
可能是什么原因？补救措施？
-
V？nligen Kerstin Viltersten
（酷长颈鹿）
2007-05-11 23:01，The Cool Giraffe写道：
我无法制作以下行编译。
int a = round（2.6）;
我当然包括< cmathand我可以去地板并且
上限没有问题。然而，四舍五入似乎并没有完全发挥作用。编译器咆哮说：
错误3错误C3861：''round''：找不到标识符
这是'这个故事的结尾。我可以（并且很可能是
）只需添加0.5和地板 - 如果结果但是
那是'错了，所以错了......
可能是什么原因？补救措施？
快速查看标准给出的答案是没有圆（）
函数。解决方法是获得符合C99标准的库并包括
< math.h（圆形（）首先包含在C99中）。
-
Erik Wikstr？m
5月11日下午5:01，The Cool Giraffe < giraf ... @ viltersten.com>
写道：
我无法编译以下行。
int a = round（2.6）;
我当然包括< cmathand我可以去地板和
上限没有问题。然而，四舍五入似乎并没有完全发挥作用。编译器咆哮说：
错误3错误C3861：''round''：找不到标识符
这是'这个故事的结尾。我可以（并且很可能是
）只需添加0.5和地板 - 如果结果但是
那是'错了，所以错了......
可能是什么原因？补救措施？
-
V？nligen Kerstin Viltersten
（酷长颈鹿）
round（）没有返回int，虽然这不是你的问题。
#include< iostream>
#include< cmath>
int main（）
{
double result = round（2.6）;
std :: cout<< " result =" <<结果<< std :: endl;
}
如果你真的需要一个int，请使用static_cast< int>（）
Erik Wikstr？m写道：
2007-05 -11 23：01，The Cool Giraffe写道：
>我无法编译以下行。
int a = round （2.6）;
我当然包括< cmathand我可以去地板和天花板没有问题。但是，四舍五入似乎根本不起作用。编译器咆哮说：
错误3错误C3861：''round''：找不到标识符
这就是这个故事的结尾。我可以（而且很可能是
会）简单地添加0.5和地板 - 如果结果但是
这是错的，所以错了......
什么可以原因？补救措施？
快速查看标准会给出答案，即没有圆形（）
函数。解决方法是获得符合C99标准的库并包括
< math.h（圆形（）首先包含在C99中）。
如果您的编译器的C模式使用C99库，您可能只需将标题更改为< math.h>
即可。
-
Ian Collins。
I have trouble making the following line compile.
int a = round (2.6);
I have, of course, included <cmathand i can go flooring and
ceiling with no problems. However, the rounding seems not to
be working at all. The compiler barks out that:
Error 3 error C3861: ''round'': identifier not found
and that''s the end of this story. I can (and most likely
will) simply add 0.5 and the floor-ify the result but
that''s just wrong, so wrong...
What can be the reason? The remedy?
--
V?nligen Kerstin Viltersten
(The Cool Giraffe)
On 2007-05-11 23:01, The Cool Giraffe wrote:I have trouble making the following line compile.
int a = round (2.6);
I have, of course, included <cmathand i can go flooring and
ceiling with no problems. However, the rounding seems not to
be working at all. The compiler barks out that:
Error 3 error C3861: ''round'': identifier not found
and that''s the end of this story. I can (and most likely
will) simply add 0.5 and the floor-ify the result but
that''s just wrong, so wrong...
What can be the reason? The remedy?A quick look in the standard gives that answer that there is no round()
function. The remedy is to get a C99 compliant library and include
<math.h(round() was included first in C99).
--
Erik Wikstr?m
On May 11, 5:01 pm, "The Cool Giraffe" <giraf...@viltersten.com>
wrote:I have trouble making the following line compile.
int a = round (2.6);
I have, of course, included <cmathand i can go flooring and
ceiling with no problems. However, the rounding seems not to
be working at all. The compiler barks out that:
Error 3 error C3861: ''round'': identifier not found
and that''s the end of this story. I can (and most likely
will) simply add 0.5 and the floor-ify the result but
that''s just wrong, so wrong...
What can be the reason? The remedy?
--
V?nligen Kerstin Viltersten
(The Cool Giraffe)round() doesn''t return an int, although thats not your problem.
#include <iostream>
#include <cmath>
int main()
{
double result = round( 2.6 );
std::cout << "result = " << result << std::endl;
}
if you really need an int, use a static_cast< int >( )
Erik Wikstr?m wrote:On 2007-05-11 23:01, The Cool Giraffe wrote:>I have trouble making the following line compile.
int a = round (2.6);
I have, of course, included <cmathand i can go flooring and
ceiling with no problems. However, the rounding seems not to
be working at all. The compiler barks out that:
Error 3 error C3861: ''round'': identifier not found
and that''s the end of this story. I can (and most likely
will) simply add 0.5 and the floor-ify the result but
that''s just wrong, so wrong...
What can be the reason? The remedy?
A quick look in the standard gives that answer that there is no round()
function. The remedy is to get a C99 compliant library and include
<math.h(round() was included first in C99).
You might be able to get away with just changing the header to <math.h>
if your compiler''s C mode uses the C99 library.
--
Ian Collins.
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