54 lines
1.3 KiB
C++
54 lines
1.3 KiB
C++
// wrapped2.cpp -- callable types and templates
|
|
#include <iostream>
|
|
#include <math.h>
|
|
#include <functional>
|
|
using namespace std;
|
|
|
|
template <typename T>
|
|
T use_f(T v, std::function<T(T)> f)
|
|
{
|
|
static int count = 0;
|
|
count++;
|
|
cout << " use_f count = " << count << ", &count = " << &count << endl;
|
|
return f(v);
|
|
}
|
|
|
|
class Fp
|
|
{
|
|
private:
|
|
double z_;
|
|
public:
|
|
Fp(double z = 1.0) : z_(z) {}
|
|
double operator()(double p) { return z_*p; }
|
|
};
|
|
class Fq
|
|
{
|
|
private:
|
|
double z_;
|
|
public:
|
|
Fq(double z = 1.0) : z_(z) {}
|
|
double operator()(double q) { return z_+ q; }
|
|
};
|
|
|
|
double dub(double x) {return 2.0*x;}
|
|
|
|
int main()
|
|
{
|
|
double y = 1.21;
|
|
cout << "Function pointer dub:\n";
|
|
cout << " " << use_f<double>(y, dub) << endl;
|
|
cout << "Function pointer sqrt:\n";
|
|
cout << " " << use_f<double>(y, sqrt) << endl;
|
|
cout << "Function object Fp:\n";
|
|
cout << " " << use_f<double>(y, Fp(5.0)) << endl;
|
|
cout << "Function object Fq:\n";
|
|
cout << " " << use_f<double>(y, Fq(5.0)) << endl;
|
|
cout << "Lambda expression 1:\n";
|
|
cout << " " << use_f<double>(y, [](double u) {return u*u;}) << endl;
|
|
cout << "Lambda expression 2:\n";
|
|
cout << " " << use_f<double>(y, [](double u) {return u+u/2.0;}) << endl;
|
|
|
|
cin.get();
|
|
return 0;
|
|
}
|