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Is std::vector so much slower than plain arrays?
... created. What happens if we change Pixel to:
struct Pixel
{
unsigned char r, g, b;
};
Result: about 10% faster. Still slower than an array. Hm.
# ./vector
UseArray completed in 3.239 seconds
UseVector completed in 5.567 seconds
Idea #4 - Use iterator instead of loop index
How about usin...
How to use sed to replace only the first occurrence in a file?
... then only looked for starting on the next line. Therefore, both lines are selected in this case, and the s/foo/bar/ substitution is performed on both of them.
sed '1,/foo/ s//bar/' <<<$'1foo\n2foo\n3foo' fails: with sed: first RE may not be empty (BSD/macOS) and sed: -e expression #1, char...
Why does Java's hashCode() in String use 31 as a multiplier?
... for 31 since 33 is not a prime:
Of the remaining
four, I'd probably select P(31), as it's the cheapest to calculate on a RISC
machine (because 31 is the difference of two powers of two). P(33) is
similarly cheap to calculate, but it's performance is marginally worse, and
33 is composit...
Splitting String with delimiter
...
Oh, and be careful if you're splitting on certain characters like a pipe |. You will need to escape the char stackoverflow.com/questions/3842537/…
– Snekse
Dec 23 '15 at 17:19
...
How to check if a String contains only ASCII?
The call Character.isLetter(c) returns true if the character is a letter. But is there a way to quickly find if a String only contains the base characters of ASCII?
...
Best practices for circular shift (rotate) operations in C++
...lude <stdint.h> // for uint32_t
#include <limits.h> // for CHAR_BIT
// #define NDEBUG
#include <assert.h>
static inline uint32_t rotl32 (uint32_t n, unsigned int c)
{
const unsigned int mask = (CHAR_BIT*sizeof(n) - 1); // assumes width is a power of 2.
// assert ( (c<...
In-memory size of a Python structure
...
@AlexMartelli Hi Alex! .. Why minimum size of a char in python is 25 bytes. >>> getsizeof('a') gives 25 and >>> getsizeof('ab') gives 26 `
– Grijesh Chauhan
Jan 17 '13 at 5:13
...
C++对象布局及多态探索之菱形结构虚继承 - C/C++ - 清泛网 - 专注C/C++及内核技术
...
{
C041() : c_(0x01) {}
virtual void foo() { c_ = 0x02; }
char c_;
};
struct C100 : public virtual C041
{
C100() : c_(0x02) {}
char c_;
};
struct C101 : public virtual C041
{
C101() : c_(0x03) {}
char c_;
};
struct C110 : public C100, public C101 ...
VC/Linux C++ 递归访问目录下所有文件 - C/C++ - 清泛网 - 专注C/C++及内核技术
... C++ 递归访问目录下所有文件VC函数，部分代码如下：find(char * lpPath){ char szFind[MAX_PATH]; WIN32_FIND_DATA FindFileData; strcpy(sz...VC函数，部分代码如下：
find(char * lpPath)
{
char szFind[MAX_PATH];
WIN32_FIND_DATA FindFileData;
strcpy...