Random vector

Last post it was about lambdas but, indeed, I just focused with an utility; random vectors creation. Now, after still being researching I found more intuitive and elegant forms.

Let's see this amazing things:

#include <algorithm>
#include <iostream>
#include <vector>
#include <time.h>

//Start reading inside main!!!!
//first template is the rank of numbers we want
//second, where it starts
template<int N, int Start = 0>
class MyRand{
public:
     int operator()(void){
         return std::rand()%N + Start;
     }
};

int fRand(){
     return std::rand()%10 + 30;
}

int main()
{
      // Create a vector object that contains 10 elements.
      std::vector<int> a(10);

     // randomly initialize using lambda expressions
     srand((unsigned)time(0)); 

     //generating the vector by means of standard random function
     //This is nice but you don't have much control of which rank of numbers
     //will be returned. Indeed, you know, with the macro RAND_MAX
     //and this is a huge number.

     //And that perhaps isn't what we expected. So the solucion is to use
     //a custom function:
     std::generate(a.begin(), a.end(), std::rand );

     //Now, just changing fRand we can get our wished numbers, but
     //even that is not the best way because you can't use any function
     //that takes some parameter and then you'd need as many function
     //as you need; and that can be tedious. Instead of this, we can use templates
     //which we won't get that problem.
     std::generate(a.begin(), a.end(), fRand );

     //So, here we go:
     //With two templated parameters we can get any random rank of numberes we want.
     //for example, if we want numbers between 10 and 20 that's the example:
     std::generate(a.begin(), a.end(), MyRand<10,10>() );

     //O maybe we want numbers between 14 and 71
     //how many numbers there are between them? 71 - 14 = 57 and we start at 14
     //So:
     std::generate(a.begin(), a.end(), MyRand<57,14>() );


     //like last time, how to write this vector with just code a line
     std::for_each(a.begin(), a.end(), [](int a){ std::cout << a << std::endl; } );
     return 0;
}