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When to use enumerateObjectsUsingBlock vs. for
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Ultimately, use whichever pattern you want to use and comes more naturally in the context.
While for(... in ...) is quite convenient and syntactically brief, enumerateObjectsUsingBlock: has a number of features that may or may not prove interesting:
enumerateObjectsUsingBlock: will be as fas...
What is “vectorization”?
...vec" instructions, and even some ARM chips have a vector instruction set, called NEON.
"Vectorization" (simplified) is the process of rewriting a loop so that instead of processing a single element of an array N times, it processes (say) 4 elements of the array simultaneously N/4 times.
(I chose 4...
What do people find difficult about C pointers? [closed]
...duling, actual CPU operations, or assembly-level memory management isn't really required.
When I was teaching, I found the following holes in students' understanding to be the most common source of problems:
Heap vs Stack storage. It is simply stunning how many people do not understand this, even...
[科普] __MACOSX是什么文件夹？ - 更多技术 - 清泛网 - 专注C/C++及内核技术
...者就可以把这个压缩包上传到网上供人下载。但是有一个问题，苹果公司和其它的大的软件公司一样，十分擅长曲解和附会用户的意思，它很多时候并不是完全按照你的意思去做的。例如在这种情况下，你以为Mac仅仅是把你想要...
大数据时代的数据化运营 - 资讯 - 清泛网 - 专注C/C++及内核技术
...下，我们在运营中看到可以获得有效数据的原始数据不是问题，去除无效和虚假的数据才是关键。
相信做发行的同行都知道，在实践中，会遇到通过某些渠道或者是CPS，或者是广告渠道，他们一定会有大量的虚假的数据在里面...
Why is there huge performance hit in 2048x2048 versus 2047x2047 array multiplication?
...he misses on matice1 are not the problem because they are accessed sequentially.
However for matice2 if a full column fits in L2 (i.e when you access matice2[0, 0], matice2[1, 0], matice2[2, 0] ... etc, nothing gets evicted) than there is no problem with cache misses with matice2 either.
Now to go ...
Why is IntelliJ 13 IDEA so slow after upgrading from version 12?
While using IntelliJ 13 ultimate edition for a week, it just seems really slow.
20 Answers
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Select n random rows from SQL Server table
...the key scan of values plus the join cost, which on a large table with a small percentage selection should be reasonable.
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Divide a number by 3 without using *, /, +, -, % operators
...n which performs the desired operation. But it requires the + operator, so all you have left to do is to add the values with bit-operators:
// replaces the + operator
int add(int x, int y)
{
while (x) {
int t = (x & y) << 1;
y ^= x;
x = t;
}
return y;
}...
What is “thread local storage” in Python, and why do I need it?
In Python specifically, how do variables get shared between threads?
5 Answers
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