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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...
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...
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...
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 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...
How do I use vimdiff to resolve a git merge conflict?
...ked in your source branch (where you are merging from). The middle buffer (BASE) is the common ancestor of the two (so you can compare how the left and right versions have diverged from each other).
I may be mistaken on the following point. I think the source of the merge conflict is that both file...
Hashing a dictionary?
...nto nested tuples and make_hash_sha256() will also convert the repr() to a base64 encoded SHA256 hash.
import hashlib
import base64
def make_hash_sha256(o):
hasher = hashlib.sha256()
hasher.update(repr(make_hashable(o)).encode())
return base64.b64encode(hasher.digest()).decode()
def m...
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 ...
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...
Objective-C and Swift URL encoding
...aractersInString:@" \"#%/:<>?@[\\]^`{|}"] invertedSet];
Creating a Base64
In the case of Base64 characterset:
NSCharacterSet *URLBase64CharacterSet = [[NSCharacterSet characterSetWithCharactersInString:@"/+=\n"] invertedSet];
For Swift 3.0:
var escapedString = originalString.addi...