#include    <iostream>
#include    <vector>
#include    <algorithm>
using namespace std;
double gen1(double, double){return 1;}
double gen1(double){return 2;}
void    Genetate(double* _beg, double* _end, double (*op)(double, double))
{
    for (;_beg!=_end;++_beg)
        *_beg=op(0,0);
}
//Genetate是一个普通函数的时候根据原型可以匹配
//Genetate是一个模板的时候无法解析
int main()
{
    vector<double> v(20);
    Genetate(v.begin(),v.end(),gen1);
    copy(v.begin(),v.end(),ostream_iterator<double>(cout, "\t"));
    return 0;
}

#include <vector>
#include <functional>
#include <algorithm>
#include <iostream>

using namespace std;

struct genfun {

    genfun() : _d1(0.0), _d2(1.0) {

    }

    genfun(const double d1, const double d2) 
        : _d1(d1), _d2(d2) {

    }

    double operator()() {
        return _d1 + (static_cast<double>(rand()) / RAND_MAX) * (_d2 - _d1);
    }

private :
    double _d1;
    double _d2;
};

int main() {

    vector<double> vd(5);

    generate(vd.begin(), vd.end(), genfun());
    for (size_t i = 0; i < vd.size(); ++i)
        cout<<vd[i]<<" ";
    cout<<endl<<endl;

    generate(vd.begin(), vd.end(), genfun(5.0, 15.3));
    for (size_t i = 0; i < vd.size(); ++i)
        cout<<vd[i]<<" ";
    cout<<endl<<endl;

    return 0;
}


----------

0.00125126 0.563585 0.193304 0.808741 0.585009

9.94269 8.608 14.2284 13.4753 12.69