I have a computer with 1 MB of RAM and no other local storage. I must use it to accept 1 million 8-digit decimal numbers over a TCP connection, sort them, and then send the sorted list out over another TCP connection. The list of numbers may contain duplicates, which I must not discard. The code will be placed in ROM, so I need not subtract the size of my code from the 1 MB. I already have code to
Runnable examples Let's create and run some minuscule bare metal hello world programs that run without an OS on: an x86 Lenovo Thinkpad T430 laptop with UEFI BIOS 1.16 firmware an ARM-based Raspberry Pi 3 We will also try them out on the QEMU emulator as much as possible, as that is safer and more convenient for development. The QEMU tests have been on an Ubuntu 18.04 host with the pre-packaged QE
In scatter and gather (i.e. readv and writev), Linux reads into multiple buffers and writes from multiple buffers. If say, I have a vector of 3 buffers, I can use readv, OR I can use a single buffer, which is of combined size of 3 buffers and do fread. Hence, I am confused: For which cases should scatter/gather be used and when should a single large buffer be used?
I thought this was asked already, but, if so, the question isn't apparent in the "related" bar. So, here it is: What is a View Bound? A view bound was a mechanism introduced in Scala to enable the use of some type A as if it were some type B. The typical syntax is this: def f[A <% B](a: A) = a.bMethod In other words, A should have an implicit conversion to B available, so that one can call B metho
blocking is meant to act as a hint to the ExecutionContext that the contained code is blocking and could lead to thread starvation. This will give the thread pool a chance to spawn new threads in order to prevent starvation. This is what is meant by "adjust the runtime behavior". It's not magic though, and won't work with every ExecutionContext. Consider this example: import scala.concurrent._ val
The short answer is YES, PDO prepares are secure enough if used properly. I'm adapting this answer to talk about PDO... The long answer isn't so easy. It's based off an attack demonstrated here. The Attack So, let's start off by showing the attack... $pdo->query('SET NAMES gbk'); $var = "\xbf\x27 OR 1=1 /*"; $query = 'SELECT * FROM test WHERE name = ? LIMIT 1'; $stmt = $pdo->prepare($query); $stmt
I can see in the API docs for Predef that they're subclasses of a generic function type (From) => To, but that's all it says. Um, what? Maybe there's documentation somewhere, but search engines don't handle "names" like "<:<" very well, so I haven't been able to find it. Follow-up question: when should I use these funky symbols/classes, and why?
While going through Functional Programming in Scala, I came across this question: Can you right foldLeft in terms of foldRight? How about the other way around? In solution provided by the authors they have provided an implementation as follows: def foldRightViaFoldLeft_1[A,B](l: List[A], z: B)(f: (A,B) => B): B = foldLeft(l, (b:B) => b)((g,a) => b => g(f(a,b)))(z) def foldLeftViaFoldRight[A,B](l:
The ScalaDoc says this about concurrentMap: "Deprecated (Since version 2.10.0) Use scala.collection.concurrent.Map instead." Unfortunately, the rest of the Scala docs has not been updated and still references concurrentMap. I tried to mix in concurrent.Map into a HashMap, with the following results: scala> val mmap = new mutable.HashMap[String, String] with collection.concurrent.Map[String, String
Per the Java documentation, the hash code for a String object is computed as: s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1] using int arithmetic, where s[i] is the ith character of the string, n is the length of the string, and ^ indicates exponentiation. Why is 31 used as a multiplier? I understand that the multiplier should be a relatively large prime number. So why not 29, or 37, or even 97?
I am doing some numerical optimization on a scientific application. One thing I noticed is that GCC will optimize the call pow(a,2) by compiling it into a*a, but the call pow(a,6) is not optimized and will actually call the library function pow, which greatly slows down the performance. (In contrast, Intel C++ Compiler, executable icc, will eliminate the library call for pow(a,6).) What I am curio
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