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C语言结构体里的成员数组和指针 - c++1y / stl - 清泛IT社区，为创新赋能！
...问0x4的内存地址，不crash才怪。于是，你一定会有如下的问题：1）为什么不是 13行if语句出错？f.a被初始化为空了嘛，用空指针访问成员变量为什么不crash？2）为什么会访问到了0x4的地址？靠，4是怎么出来的？3）代码中的第4行...
How many system resources will be held for keeping 1,000,000 websocket open? [closed]
...active socket connections is possible for a properly sized system (lots of CPU, RAM and fast networking) and with a tuned server system and optimized server software.
The number of connections is not the primary problem (that's mostly just a question of kernel tuning and enough memory), it is the p...
What's the difference between a word and byte?
... or even 12 bit machines.
The byte is the smallest addressable unit for a CPU. If you want to set/clear single bits, you first need to fetch the corresponding byte from memory, mess with the bits and then write the byte back to memory.
The word by contrast is biggest chunk of bits with which a pro...
What is the “volatile” keyword used for?
...with "preventing caching". It is about reordering, by the compiler, OR the CPU hardware through speculative execution.
– doug65536
Oct 7 '16 at 2:52
...
What's the Android ADB shell “dumpsys” tool and what are its benefits?
...m information in a simple string representation.
Possibility to use dumped CPU, RAM, Battery, storage stats for a
pretty charts, which will allow you to check how your application
affects the overall device!
What information can we retrieve from dumpsys shell command and how we can use it
If you ...
How to make execution pause, sleep, wait for X seconds in R?
...(x)
{
p1 <- proc.time()
Sys.sleep(x)
proc.time() - p1 # The cpu usage should be negligible
}
testit(3.7)
Yielding
> testit(3.7)
user system elapsed
0.000 0.000 3.704
share
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为何谷歌不可复制？ - 资讯 - 清泛网 - 专注C/C++及内核技术
...可使用并从中受益，那么糟糕的广告(即信息)就自然是个问题了。因此，即使牺牲周末时间，他们也决定解决这个问题。”
谷歌之所以成为后德鲁克时代最具代表性的公司，除了两位创始人的学院派的作风外，谷歌公司也延续...
What is the purpose of XORing a register with itself? [duplicate]
...it the fastest way it knows. A bit operation like XOR might take only one CPU cycle, whereas a copy (from one register to another) can take a small handful.
Often compiler writers will even have different behaviors given different target CPU architectures.
...
John Carmack's Unusual Fast Inverse Square Root (Quake III)
...ng result, until required accuracy is met. This is exactly how it works in CPU/FPU! But it seems that only one iteration was enough, which was also a blessing for the speed. CPU/FPU does as many iterations as needed to reach the accuracy for the floating point number in which the result is stored an...
社会化海量数据采集爬虫框架搭建 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...果能把账号和IP的访问策略控制好了，基本可以解决这个问题了。当然对方网站也会有运维会调整策略，说到底这是一个战争，躲在电脑屏幕后的敌我双方，爬虫必须要能感知到对方的反监控策略进行了调整，通知管理员及时处...