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Fastest way to determine if an integer's square root is an integer
... doing a bit-wise "and." Perfect squares can only end in 0, 1, 4, or 9 in base 16, So for 75% of your inputs (assuming they are uniformly distributed) you can avoid a call to the square root in exchange for some very fast bit twiddling.
Kip benchmarked the following code implementing the hex tric...
Beyond Stack Sampling: C++ Profilers
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I asked this question Linux time sample based profiler. OProfile is supposed the get time based sampling eventually. They produce very high quality output, so once they add that feature I'll use them. Other than that I had a friend hack together a gdb + backtrace...
Obfuscated C Code Contest 2006. Please explain sykes2.c
...it.
Indenting:
main(_) {
_^448 && main(-~_);
putchar(--_%64
? 32 | -~7[__TIME__-_/8%8][">'txiZ^(~z?"-48] >> ";;;====~$::199"[_*2&8|_/64]/(_&2?1:8)%8&1
: 10);
}
Introducing variables to untangle this mess:
main(int i) {
if(i^448)
m...
Using the rJava package on Win7 64 bit with R
I'm trying to install rJava on a computer with Win 7 64 bit. When I run
12 Answers
1...
Xcode 5.1 - No architectures to compile for (ONLY_ACTIVE_ARCH=YES, active arch=x86_64, VALID_ARCHS=i
After updating to Xcode 5.1, I can no longer build my project for the 64-bit simulator, receiving this error:
18 Answers
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How to detect total available/free disk space on the iPhone/iPad device?
...m.
Original answer:
I found the following solution working for me:
-(uint64_t)getFreeDiskspace {
uint64_t totalSpace = 0;
uint64_t totalFreeSpace = 0;
NSError *error = nil;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSD...
Hash and salt passwords in C#
...you must convert a hash to its string representation you can use Convert.ToBase64String and Convert.FromBase64String to convert it back.
You should note that you cannot use the equality operator on byte arrays, it checks references and so you should simply loop through both arrays checking each byt...
How to use Boost in Visual Studio 2010
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Run b2:
Win32: b2 --toolset=msvc-10.0 --build-type=complete stage ;
x64: b2 --toolset=msvc-10.0 --build-type=complete architecture=x86 address-model=64 stage
Go for a walk / watch a movie or 2 / ....
Go through steps 2 - 6 from the set of instruction above to set the environment varia...
64 bit OS下int占几个字节？ - C/C++ - 清泛网 - 专注C/C++及内核技术
64 bit OS下int占几个字节？int固定4字节，不要受64 bit的混淆。int是由编程语言设计决定的，不受编译器的影响。__int64才是8位的。另外，指针是受编译器 OS影响的，3...int固定4字节，不要受64 bit的混淆。int是由编程语言设计决定的...
How to make rpm auto install dependencies
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No, this will not work unless libtest1-1.0-1.x86_64.rpm is in a repository elsewhere, or both packages are specified on the command line like "rpm -i" would require. I just verified this on yum 3.4.3 (Fedora 18). Transcript here showing that it goes to the updates repo for ...