How to use std iterator with basic type uint8 t

Question

I was going through a code on https://github.com/bitcoin/bitcoin/blob/master/src/uint256.cpp#L23

that traverses array of uint8_t using std::reverse_iterator<const uint8_t*>.

The code snippet is as follows:

#include <stdint.h>

#include <iterator>

#include <iostream>


using namespace std;

uint8_t data[8] = {0, 1, 2, 3, 4, 5, 6, 7};


template<typename T>

void HexStr(const T itbegin, const T itend)

{

    for (T it = itbegin; it < itend; ++it)

    {

        cout << +*it << " ";

    }

    cout << endl;

}


int main()

{

    HexStr(reverse_iterator<const uint8_t*>(data + sizeof(data)),

           reverse_iterator<const uint8_t*>(data));


    return 0;

}

Why I can not I do the same thing using using a regular iterator (std::iterator<const uint8_t*>.

When I tried, I get the following error:

error: wrong number of template arguments (1, should be at least 2).

Can somebody tell me why this is happening?

Answer 1

std::reverse_iterator takes the original iterator type as template parameter.

Thus the type you're looking for is const uint8_t*, not std::iterator<const uint8_t*>