什么<<用C ++表示？ [英] What does << mean in C++?

问题描述

以下宏意味着什么，尤其是<<标志：


#define hello（x）（（int64）floor（（double）x）<< 32）


谢谢

Thierry

解决方案

Thierry Lam写道：

以下宏意味着什么，特别是<< sign：


#define hello（x）（（int64）floor（（double）x）<< 32）

你应该得到一本C ++书。这是一个非常基本的概念。 <<是位移

运算符。在这里，这意味着左侧的值应该是32位左移。

Rolf Magnus写道：

Thierry Lam写道：

以下宏意味着什么，特别是<< sign：


#define hello（x）（（int64）floor（（double）x）<< 32）

你应该得到一本C ++书。

同意。这里有一个好的，免费的：

http://mindview.net/Books/TICPP/ThinkingInCPP2e.html

或由Koenig和Moo获得_Accelerated C ++ _，这是最好的恕我直言。


干杯！ --M

mlimber写道：

Rolf Magnus写道：
< blockquote class =post_quotes>
>> Thierry Lam写道：

>>>以下宏是什么意思是，特别是<< sign：

#define hello（x）（（int64）floor（（double）x）<< 32）

你应该得到一个C ++书。

同意。这里有一个好的，免费的：

http://mindview.net/Books/TICPP/ThinkingInCPP2e.html

或由Koenig和Moo获得_Accelerated C ++ _，这是最好的恕我直言。


干杯！ --M

C ++与它无关......看起来它只是找到变量x的

数学底层（最大积分值小于

或等于x）并将其右移到4个最重要的字节......

What does the following macro mean, especially the << sign:

#define hello(x) (( int64 ) floor( (double) x ) << 32)

Thanks
Thierry

解决方案

Thierry Lam wrote:

What does the following macro mean, especially the << sign:

#define hello(x) (( int64 ) floor( (double) x ) << 32)

You should get a C++ book. This is a very basic concept. << is the bit shift
operator. Here, it means that the value on the left side should be shift
left by 32 bits.

Rolf Magnus wrote:

Thierry Lam wrote:

What does the following macro mean, especially the << sign:

#define hello(x) (( int64 ) floor( (double) x ) << 32)

You should get a C++ book.

Agreed. There''s a good, free one here:

http://mindview.net/Books/TICPP/ThinkingInCPP2e.html

or get _Accelerated C++_ by Koenig and Moo, which is the best IMHO.

Cheers! --M

mlimber wrote:

Rolf Magnus wrote:

>>Thierry Lam wrote:

>>>What does the following macro mean, especially the << sign:

#define hello(x) (( int64 ) floor( (double) x ) << 32)

You should get a C++ book.

Agreed. There''s a good, free one here:

http://mindview.net/Books/TICPP/ThinkingInCPP2e.html

or get _Accelerated C++_ by Koenig and Moo, which is the best IMHO.

Cheers! --M

C++ has nothing to do with it... looks like it is just finding the
mathematical floor of the variable x (largest integral value less than
or equal to x) and right shifting it into the 4 most significant bytes...

这篇关于什么&lt;&lt;用C ++表示？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！