Zapisanie do pliku .txt kilku wartosci powoduje koniecznosc ponownego podania parametrow

//calculates lattice parameters and outputs a txt file with them

#include <iostream>
#include <math.h>
#include <cstdlib>
#include <cmath>
#include <iomanip>
#include <fstream>

#define M_PI 3.14159265358979323846

int millerIndexH()
{
    int h;
    std::cout << "Input h index" << std::endl; //input of Miller index h
    std::cin >> h;
    return h;
}

int millerIndexK()
{
    int k;
    std::cout << "Input k index" << std::endl; //input of Miller index k
    std::cin >> k;
    return k;
}

int millerIndexL()
{
    int l;
    std::cout << "Input l index" << std::endl; //input of Miller index l
    std::cin >> l;
    return l;
}

long double defineWaveLength()
{
    std::cout << "\n";
    std::cout << "Predefined sources\n";
    std::cout << "\n1 - CuKa\n 2 - CrKa\n 3 - FeKa\n 4 - CoKa\n 5 - MoKa\n 6 - AgKa\n 0 - other\n";
    std::cout << "Choose source: ";
    int choice;
    std::cin >> choice;
    std::cout << "\n";
   
    if( choice == 1 )
    {
        long double wl;
        wl = 1.5406;
        return wl;
    }
    if( choice == 2 )
    {
        long double wl;
        wl = 2.29;
        return wl;
    }
    if( choice == 3 )
    {
        long double wl;
        wl = 1.94;
        return wl;
    }
    if( choice == 4 )
    {
        long double wl;
        wl = 1.79;
        return wl;
    }
    if( choice == 5 )
    {
        long double wl;
        wl = 0.71;
        return wl;
    }
    if( choice == 6 )
    {
        long double wl;
        wl = 0.56;
        return wl;
    }
    if( choice == 0 )
    {
        std::cout << "Input wavelength" << std::endl;
        long double wl;
        std::cin >> wl;
        return wl;
    }
    return 0;
}

long double doubleThetaDegrees() //takes double theta angle in degrees
{
    long double t_deg;
    std::cout << "Input double theta in degrees" << std::endl;
    std::cin >> t_deg;
    std::cin.ignore(); //placing it in main() right before cin.get() does diddly squat
    return t_deg;
}

long double tInRadians() //converts theta() from degrees to radians
{
    long double t_deg = doubleThetaDegrees();
    long double t_rad;
    t_rad =(( t_deg ) / 2 ) *( M_PI / 180 );
    return t_rad;
}

long double latticeSpacing() //calculate lattice spastd::cing
{
    long double wl = defineWaveLength();
    long double t_rad = tInRadians();
    long double d;
    d =( wl /( 2 * sin( t_rad ) ) );
    return d;
}

long double latticeConstantCalculation() //calculate the constant
{
    int h = millerIndexH();
    int k = millerIndexK();
    int l = millerIndexL();
    long double d = latticeSpacing();
    long double a;
    a = sqrt(( pow( h, 2 ) + pow( k, 2 ) + pow( l, 2 ) ) *( pow( d, 2 ) ) ); //proper equation
    return a;
}

int main()
{
    int h = millerIndexH();
    int k = millerIndexK();
    int l = millerIndexL();
    long double d = latticeSpacing();
    long double a = latticeConstantCalculation();
    std::cout << "(" << h << k << l << ")" << "\t" << a << "\t" << d << std::endl; //shows result
    std::ofstream o( "Lattice Parameters.txt", std::ios::app );
    o << "Miller indecies (" << h << k << l << ")/tLattice Constant " << a << "\tLattice spacing " << d << std::endl;
    std::cin.get();
}