язык "c" не могу написать код

#include <stdio.h>
#include <iostream.h>
#include <conio.h>
#include <math.h>
#include <stdlib.h>

void main()
{
    int X=2,f=2,Y=2,w=2,key,b=2,a=2;
    int v[20];
    float G;

    cout<<"meniu:";
    cout<<"\n 1.metoda for";
    cout<<"\n 2.metoda while";
    cout<<"\n 3.metoda do";
    cout<<"\n 4.iesire";
    cout<<"\n alege metoda:";
    cin >> key;
    if((Y-(X-w)==14))
    {
        switch ( key )
        {
        case 1:
            {
                for(f=(X-w);f<Y;f++)
                {
                    G=(pow(b,2)+a-f)/sqrt(abs(a+b));
                    cout<<"ati ales metoda for\tG="<<G;
                }
                break;
            }
        case 2:
            {
                f=(X-w);

                {
                    G=(pow(b,2)+a-f)/sqrt(abs(a+b));
                    cout<<"ati ales metoda while\tG="<<G;
                    f++;
                }
                break;
            }
        case 3:
            {
                f=(X-w);
                do
                {
                    G=(pow(b,2)+a-f)/sqrt(abs(a+b));
                    cout<<"G="<<G;
                    f++;
                } while(f<Y);
                break;
            }
        case 4:
            {
            exit(0);
            }
        }
    }
    else
    {
        cout<<"\nintervalul nu se satisface";
        cout<< "\nG=" << G;
    }

    cout<<"\n\n\tPrima conditie al lucrarii practice Nr.4";

        v[20]=G;
        cout<<"\n\nv "<<G;
        cout<<"\n\n\tAdoua conditie al lucrarii practice Nr.4 \n\n";
        int Q[20] ,i ;

        randomize();
        for (i=0;i<20;i++)
        {
         cout<<" "<< Q[i];
        }

getch();
    }