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了解 Boost Filesystem Library - C/C++ - 清泛网 - 专注C/C++及内核技术
... <stdio.h>
int main()
{
struct stat s1;
int status = stat(<const char* denoting pathname>, &s1);
printf(“Path is a directory : %d\n”, S_ISDIR(s1.st_mode));
return 0;
}
对于 I/O 操作较多的程序，这样的不一致就意味着需要进行大量的工程工作才能...
Algorithm to return all combinations of k elements from n
... takes an array of letters as an argument and a number of those letters to select.
71 Answers
...
What is move semantics?
...:
#include <cstring>
#include <algorithm>
class string
{
char* data;
public:
string(const char* p)
{
size_t size = std::strlen(p) + 1;
data = new char[size];
std::memcpy(data, p, size);
}
Since we chose to manage the memory ourselves, we need...
How do I trim whitespace from a string?
... Hello ")
' Hello'
Also, note that str.strip() removes other whitespace characters as well (e.g. tabs and newlines). To remove only spaces, you can specify the character to remove as an argument to strip, i.e.:
>>> " Hello\n".strip(" ")
'Hello\n'
...
Is gcc's __attribute__((packed)) / #pragma pack unsafe?
....h>
#include <stddef.h>
int main(void)
{
struct foo {
char c;
int x;
} __attribute__((packed));
struct foo arr[2] = { { 'a', 10 }, {'b', 20 } };
int *p0 = &arr[0].x;
int *p1 = &arr[1].x;
printf("sizeof(struct foo) = %d\n", (int)sizeof(str...
Why historically do people use 255 not 256 for database field magnitudes?
You often see database fields set to have a magnitude of 255 characters, what is the traditional / historic reason why? I assume it's something to do with paging / memory limits, and performance but the distinction between 255 and 256 has always confused me.
...
“sending 'const NSString *' to parameter of type 'NSString *' discards qualifiers” warning
...he term on its right only if there's nothing on its left side (e. g. const char * and a char const * are non-const pointers to const char, but char *const is a const pointer to non-const char).
– user529758
Oct 11 '12 at 4:29
...
Why is “while ( !feof (file) )” always wrong?
...e is again std::cin, just as before.
POSIX, write(2) to flush a buffer:
char const * p = buf;
ssize_t n = bufsize;
for (ssize_t k = bufsize; (k = write(fd, p, n)) > 0; p += k, n -= k) {}
if (n != 0) { /* error, failed to write complete buffer */ }
The result we use here is k, the numb...
How to handle Objective-C protocols that contain properties?
...hInteger:(factor*amount)];
}
// <<
@end
int main(int argc, const char * argv[])
{
@autoreleasepool {
Person *duncan=[[Person alloc]initConforming];
duncan.firstname=@"Duncan";
duncan.lastname=@"Smith";
[Viewer printLargeDescription:duncan];
S...
LINQ equivalent of foreach for IEnumerable
...d evaluating Funcs
var evaluatedObservable = observable.ToEnumerable().Select(func => func()).ToList();
//Win
Assert.That(evaluatedObservable,
Is.EquivalentTo(values.ToList()));
}
The following fails with the error:
Expected: equivalent to < 0, 1, 2, 3, 4, 5, 6, 7, 8, ...