// Program Assignment #3
// Program will display a 7 option switch/case menu
// each selection has functions
#include <iostream>
#include <cstdlib> // so the program can see rand()
#include <fstream>
using namespace std; // So the program can see cout and endl

// Used Functions starts here..

void generate() // functiong for generation of numbers.
{
ofstream outputfile;

int x[100],input,y;
cout <<"Please enter a number between 10 and 100 to generate numbers.\n";
        cin >>input;
while(input <10 || input >100)
    {
    cout <<"Please enter a number between 10 and 100 to generate numbers.\n";
    cin >>input;
    }
outputfile.open("num.dat");
for (int y=0;y<input;y++)
{
    x[y]=rand();
    outputfile << x[y]<<endl;
}
outputfile.close();
}

int read_data(char n[],int y[]) // function used for reading data.
{
    int i=0;
    ifstream infile;
    infile.open(n);
    while (!infile.eof())
    {
        infile>>y[i];
        i++;
    }
    return i-1;
}

void display_data() // display data
{
    int x[100],y,i;
    y= read_data("num.dat",x);
    if (y<=0)
    {
        cout << "Reading from file failed.\n";
    }
    else
        for(i=0;i<y;i++)
            cout<<x[i]<<" "<<endl;
}


void sum_data() // sum the numbers
{
    int x[100],y,i,sum;
    y= read_data("num.dat",x);
    if (y<=0)
    {
        cout << "Reading from file failed.\n";
    }
    else
    for(i=0;i<y;i++)
        sum=sum+x[i];
    cout<< "Sum of the generated numbers is " << sum << endl;
}

void ave_data() // ave the numbers
{
    int x[100],y,i;
    double sum,ave;
    y= read_data("num.dat",x);
    if (y<=0)
    {
        cout << "Reading from file failed.\n";
    }
    else
    for(i=0;i<y;i++)
    ave=(ave+x[i])/y;
    cout<< "Average of the generated numbers is " << ave << endl;
}
void findstddev()// std deviation
{
    int x[100],y,i;
    double stddev,sum,ave;
    y= read_data("num.dat",x);
    if (y<=0)
    {
        cout << "Reading from file failed.\n";
    }
    else
    for(i=0;i<y;i++)
    {
     ave=(ave+x[i])/y;
     sum=sum+x[i];
    }
stddev=(((sum+(ave*ave))/y))/(((sum+(ave*ave))/y));
cout << "Standard deviation of the generated numbers is " << stddev << endl;
}

void finddivison() // function finds numbers divisiable by 4 & 8
{
    int x[100],y,i;
    y= read_data("num.dat",x);
    if (y<=0)
    {
        cout << "Reading from file failed.\n";
    }
    else
        for(i=0;i<y;i++)
            if(x[i]%4==0 || x[i]%8==0)
            cout<<x[i]<<" "<<endl;
}

void max_min() // finds largest & smallest number
{
    int x[100],y,i,largest=0,smallest;
    y= read_data("num.dat",x);
    if (y<=0)
    {
        cout << "Reading from file failed.\n";
    }
    else
        for(i=0;i<y;i++)
        {
            if(x[i]>largest)
            largest=x[i];
        }
        smallest=largest;
        for(i=0;i<y;i++)
            if(smallest>x[i])
            smallest=x[i];

    cout << "Maximum of the generated numbers is " << largest<<endl;
    cout << "Minumum of the generated numbers is " << smallest<<endl;
}

int main()
{
int selection;
for(int z=0;z<100;)
    {
        cout<<"1. Generate Random Numbers.\n";
        cout<<"2. Read generated numbers from file\n";
        cout<<"3. Find Sum and Average\n";
        cout<<"4. Find Maximum and Minimum\n";
        cout<<"5. Find Standard Deviation\n";
        cout<<"6. Find Numbers Divisible by 4 and 8\n";
        cout<<"7. Quit\n";
        cout<<"Selection: ";
        cin>> selection;
        switch(selection)
        {
            case 1:
            generate();
            break;
            case 2:
            display_data();
            break;
            case 3:
            sum_data();
            ave_data();
            break;
            case 4:
            max_min();
            break;
            case 5:
            findstddev();
            break;
            case 6:
            finddivison();
            case 7:
            return 1;
        }
    }
}