[toc]
Shuffle
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| static void shuffle(vector<int>* v) {
srand(9);
for (int n = v->size(); n >= 2; n--) {
swap((*v)[n - 1], (*v)[static_cast<unsigned>(rand()) % n]);
}
}
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class 成员初始化
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| $ cat 010.cpp
#include <iostream>
using namespace std;
class Plm {
public:
struct Arg {
size_t net;
size_t mem;
size_t query;
};
};
int main() {
Plm::Arg arg {
.net = 1,
.mem = 3,
.query = 2
};
cout << arg.net << " " << arg.mem << " " << arg.query << endl;
return 0;
}
$ g++ 010.cpp && ./a.out
1 3 2
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parameter pack
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| template<typename... Arguments>
void SampleFunction(Arguments... parameters);
template<typename T, typename U>
void SampleFunction(T param1, U param2);
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| bovenson@Dell:~/Git/notes/C++/Code/Learn$ cat 005.cpp
#include <iostream>
using namespace std;
void fa(int a, int b) {
cout << a << " " << b << endl;
}
template<typename... Args>
void f(Args... args) {
fa((args)...);
fa(args...);
fa(std::forward<Args>(args)...);
// fa(std::forward<Args>((args)...)); // ERROR
}
int main() {
f<int, int>(1, 2); // OK
f(1, 2); // OK
return 0;
}
bovenson@Dell:~/Git/notes/C++/Code/Learn$ g++ 005.cpp && ./a.out
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1 2
1 2
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| MBP:Learn sunzhenkai$ cat 16.cpp
#include <iostream>
#include <vector>
using namespace std;
template <typename... T>
void f(T... args) {
std::vector<int> v = { args... };
for (auto item : v) {
std::cout << item << std::endl;
}
}
int main() {
f(1, 2, 3, 4, 5);
return 0;
}
MBP:Learn sunzhenkai$ g++ 16.cpp -std=c++11 && ./a.out
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完美转发
无论是T&&、左值引用、右值引用，std::forward都会依照原来的类型完美转发。
省略号语法
Amazing
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| MBP:Learn sunzhenkai$ cat 15.cpp
#include <iostream>
using namespace std;
class A { };
class B {
public:
B(A a) {}
};
void fun(B b) {
cout << "OK? OK!" << endl;
}
int main() {
A a;
fun(a);
return 0;
}
MBP:Learn sunzhenkai$ g++ 15.cpp && ./a.out
OK? OK!
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