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Using scanf() in C++ programs is faster than using cin?
...numbers.
iostream version:
#include <iostream>
int main(int argc, char **argv) {
int parity = 0;
int x;
while (std::cin >> x)
parity ^= x;
std::cout << parity << std::endl;
return 0;
}
scanf version:
#include <stdio.h>
int main(int argc, char **a...
What is the best way to use a HashMap in C++?
...gt;
#include <iostream>
#include <cassert>
int main(int argc, char **argv)
{
std::map<std::string, int> m;
m["hello"] = 23;
// check if key is present
if (m.find("world") != m.end())
std::cout << "map contains key world!\n";
// retrieve
std::cout << m["...
boost自定义composite_key_compare比较函数 - C/C++ - 清泛网 - 专注C/C++及内核技术
...st::multi_index_container;
using namespace boost::multi_index;
typedef char IDType[81];
struct TParam
{
IDType ID;
bool IsValid;
};
typedef TParam* TParam_p;
struct TParamIDIndex { };
struct TParamValidIndex { };
struct customize_compare
{
int operator()(const IDType l, cons...
How do you compare structs for equality in C?
...use memcmp to compare structs for equality due to potential random padding characters between field in structs.
// bad
memcmp(&struct1, &struct2, sizeof(struct1));
The above would fail for a struct like this:
typedef struct Foo {
char a;
/* padding */
double d;
/* padding */
...
Omitting all xsi and xsd namespaces when serializing an object in .NET?
...e doc, when it writes it does not check for the following:
Invalid characters in attribute and element names.
Unicode characters that do not fit the specified encoding. If the Unicode
characters do not fit the specified
encoding, the XmlTextWriter does not
escape the Unicode characte...
Efficiently convert rows to columns in sql server
...ou can use the PIVOT function to transform the data from rows to columns:
select Firstname, Amount, PostalCode, LastName, AccountNumber
from
(
select value, columnname
from yourtable
) d
pivot
(
max(value)
for columnname in (Firstname, Amount, PostalCode, LastName, AccountNumber)
) piv;
S...
Check if a string contains another string
...ontains a ","(comma) in it. Do we have any other option other than reading char-by-char?
4 Answers
...
C++及Windows异常处理(try，catch; __try,__finally, __except) - C/C++ - ...
...ss File_handle {
FILE* p;
public:
File_handle(const char* n, const char* a)
{ p = fopen(n,a); if (p==0) throw Open_error(errno); }
File_handle(FILE* pp)
{ p = pp; if (p==0) throw Open_error(errno); }
~File_handle() { fclose(p); }
...
Platform independent size_t Format specifiers in c?
...
Yes: use the z length modifier:
size_t size = sizeof(char);
printf("the size is %zu\n", size); // decimal size_t ("u" for unsigned)
printf("the size is %zx\n", size); // hex size_t
The other length modifiers that are available are hh (for char), h (for short), l (for long),...
Getting a File's MD5 Checksum in Java
... byte data[] = org.apache.commons.codec.digest.DigestUtils.md5(fis); char md5Chars[] = Hex.encodeHex(data); String md5 = String.valueOf(md5Chars);`
– Dmitry_L
Jul 17 '13 at 10:45
...