PracticeDev/study_cpp/cpp_primer_source_code/Chapter 18/wrapped0.cpp

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// wrapped0.cpp -- using a function wrapper
#include "somedefs.h"
#include <iostream>
#include <math.h>
#include <functional>
double dub(double x) {return 2.0*x;}
int main()
{
using std::cout;
using std::endl;
using std::function;
typedef function<double(double)> fdd;
double y = 1.21;
function<double(double)> ef1 = dub;
function<double(double)> ef2 = std::sqrt;
function<double(double)> ef3 = Fq(10.0);
function<double(double)> ef4 = Fp(10.0);
function<double(double)> ef5 = [](double u) {return u*u;};
function<double(double)> ef6 = [](double u) {return u+u/2.0;};
cout << use_f(y, function<double(double)>(dub)) << endl;
cout << use_f(y, fdd(sqrt)) << endl;
cout << use_f(y, ef3) << endl;
cout << use_f(y, ef4) << endl;
cout << use_f(y, ef5) << endl;
cout << use_f(y, ef6) << endl;
std::cin.get();
return 0;
}