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Why is processing a sorted array faster than processing an unsorted array?
Here is a piece of C++ code that shows some very peculiar behavior. For some strange reason, sorting the data miraculously makes the code almost six times faster:
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各编程语言读写文件汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术
...ets、fputs文本读写
3.2、fread、fwrite二进制读写
四、C++
五、Java
PHP读写文件：
// 写文件
$fp = fopen("log.txt", "a");
fwrite($fp, $str);
fclose($fp);
// 读文件
$fp = fopen("log.txt", "r");
while(!feof($fp)) {
$line = fgets($fp);
echo $line;
}
...
How are virtual functions and vtable implemented?
We all know what virtual functions are in C++, but how are they implemented at a deep level?
12 Answers
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Do the parentheses after the type name make a difference with new?
...ns POD members and is using a compiler-generated default constructor.
In C++1998 there are 2 types of initialization: zero and default
In C++2003 a 3rd type of initialization, value initialization was added.
Assume:
struct A { int m; }; // POD
struct B { ~B(); int m; }; // non-POD, compiler gen...
Is it safe to use -1 to set all bits to true?
I've seen this pattern used a lot in C & C++.
20 Answers
20
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CFLAGS vs CPPFLAGS
I understand that CFLAGS (or CXXFLAGS for C++) are for the compiler, whereas CPPFLAGS is used by the preprocessor.
4 Answer...
How do I explicitly instantiate a template function?
...You can tell the compiler to explicitly instantiate templates. Google for "C++ explicit template instantiation" for more details.
– hrnt
Feb 8 '11 at 12:56
8
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How does libuv compare to Boost/ASIO?
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Scope
Boost.Asio is a C++ library that started with a focus on networking, but its asynchronous I/O capabilities have been extended to other resources. Additionally, with Boost.Asio being part of the Boost libraries, its scope is slightly narrowe...
Red black tree over avl tree
...ree is used in the following:
Java: java.util.TreeMap, java.util.TreeSet
C++ STL (in most implementations): map, multimap, multiset
Linux kernel: completely fair scheduler, linux/rbtree.h
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Size of Matrix OpenCV
...of rows in a 2D array.
mat.cols – Number of columns in a 2D array.
Or:
C++: Size Mat::size() const
The method returns a matrix size: Size(cols, rows) . When the matrix is more than 2-dimensional, the returned size is (-1, -1).
For multidimensional matrix, you need to use
int thisSizes[3] = {...