Euler Constant γ = 0.577216

#include <iostream>
#include <stdlib.h>
#include <math.h>
#include <vector>
#include <algorithm>
#define LIMITPOWER 8

using namespace std;

// Auxiliary Functions
double sumHarmonic(int a, int b){
    if(a > b){
        return -1000;
    }
    double sum = 0.0;
    for(int i=a; i<b+1; i++){
        sum += double(1) / double(i);
    }
    return sum;
}

double ln(int n){
    return log(n);
}

double calculateEulerConstant(int n){
    return sumHarmonic(1, n) - ln(n);
}

int main()
{
    vector <double> sums = vector <double> ();
    vector <double> logarithms = vector <double> ();
    vector <double> euler = vector <double> ();
    for(int i=0; i<LIMITPOWER; i++){
        sums.push_back(sumHarmonic(1, pow(10, i+1)));
        logarithms.push_back(ln(pow(10, i+1)));
        euler.push_back(calculateEulerConstant(pow(10, i+1)));
    }
    for(int i=0; i<LIMITPOWER; i++){
        cout << "~~~~~~~~ Range 1 - " << pow(10,i+1) << " ~~~~~~~~" << endl;
        cout << " 1 + 1/2 + 1/3 + .... + 1/" << pow(10, i+1) - 1 << " + 1/" <<  pow(10, i+1) << " = " << sums[i] << endl;
        cout << "ln(" << pow(10, i+1) << ") = " << logarithms[i] << endl;
        cout << "Euler constant = " << euler[i] << endl << endl;
    }
    return 0;
}