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What's the difference between IQueryable and IEnumerable
...like LINQ-to-SQL to exist because they can parse the expression tree and convert it into equivalent SQL. And because the provider doesn't need to execute until the IQueryable is enumerated (it implements IEnumerable<T>, after all), it can combine multiple query operators (in the above exampl...
Avoiding if statement inside a for loop?
...ex index = 0) {
for (const auto& e : c)
f(index++, e);
}
int main() {
using namespace std;
set<char> s{'b', 'a', 'c'};
// indices starting at 1 instead of 0
for_each_indexed(s, [](size_t i, char e) { cout<<i<<'\t'<<e<<'\n'; }, 1u);
...
How can I declare and define multiple variables in one line using C++?
...
int column = 0, row = 0, index = 0;
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What are the differences between a pointer variable and a reference variable in C++?
...
A pointer can be re-assigned:
int x = 5;
int y = 6;
int *p;
p = &x;
p = &y;
*p = 10;
assert(x == 5);
assert(y == 10);
A reference cannot, and must be assigned at initialization:
int x = 5;
int y = 6;
int &r = x;
...
Int division: Why is the result of 1/3 == 0?
...
The two operands (1 and 3) are integers, therefore integer arithmetic (division here) is used. Declaring the result variable as double just causes an implicit conversion to occur after division.
Integer division of course returns the true result of divisi...
How do I generate random integers within a specific range in Java?
How do I generate a random int value in a specific range?
66 Answers
66
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Explicit specialization in non-namespace scope [duplicate]
...ion:
namespace detail {
template <typename TL> void Verify (int, int[]) {}
template <> void Verify<int>(int, int[]) {}
}
template<typename T> class CConstraint {
// ...
template <typename TL> void Verify(int position, int constraints[]) ...
Macro vs Function in C
...ample, this macro:
#define square(a) a * a
works fine when used with an integer:
square(5) --> 5 * 5 --> 25
but does very strange things when used with expressions:
square(1 + 2) --> 1 + 2 * 1 + 2 --> 1 + 2 + 2 --> 5
square(x++) --> x++ * x++ --> increments x twice
Putt...
How can I record a Video in my Android App.?
...der.prepare();
} catch (IllegalStateException e) {
e.printStackTrace();
finish();
} catch (IOException e) {
e.printStackTrace();
finish();
}
}
public void onClick(View v) {
if (recording) {
recorder....
C++中智能指针的设计和使用 - C/C++ - 清泛网 - 专注C/C++及内核技术
C++中智能指针的设计和使用 智能指针(smart pointer)是存储指向动态分配（堆）对象指针的类，用于生存期控制，能够确保自动正确的销毁动态分配的对象，防止内存泄露。它的一种通用实现技术是使用引用计 智能指针(smart p...