import java.util.Scanner;

public class Ch4
{
    public void workWithStrings()
    {   // concatenation:
        String name = "Dave";
        String msg = "Hello, " + name;
        
        String a = "Agent";
        int n = 7;
        String bond = a + n;
        
        // convert a String to an integer:
        String num = "3";
        int num2 = Integer.parseInt(num);
        
        //convert a String to a double:
        String num5 = "3.14159";
        double num6 = Double.parseDouble(num5);
        
        // convert an int to a String:
        int num3 = 3;
        String num4 = String.valueOf(num3);
        
        // substrings
        name = "Aanya Tripathi";
        // gets characters from position 0 to 5:
        String name2 = name.substring(0,6);
        System.out.println("name2: " + name2);
        
        // another substring example:
        // gets characters from position 6
        // to the end of the String:
        String name3 = name.substring(6);
        System.out.println("name3: " + name3);
          
    }
    public void readInput()
    {   // uses Scanner class
        Scanner in = new Scanner(System.in);
        System.out.print("Integer: >");
        int a2 = in.nextInt();
        System.out.print("Double: >");
        double b2 = in.nextDouble();
        System.out.print("Enter state code: >");
        String state = in.next();
    }
    public void doMath()
    {   // use parentheses when needed:
        int a = 7; int b = 9;
        int avg = (a + b) / 2;
        int items = 5;
        // increment:
        items++;
        
        // decrement:
        items--;
        
        // integer division
        // the result of dividing 2 int's is an int
        int x = 7/5;
        System.out.println("result: " + x);
        double y = 7./5;
        System.out.println("result: " + y);
        
        // modular division (keep the remainder)
        int z = 7 % 5;
        System.out.println("result: " + z);
        
        // square root:
        double bb = Math.sqrt(100);
        System.out.println("result: " + bb);
        
        // raising a number to a power:
        double cc = Math.pow(4, 3);
        int ee = (int) cc;
        System.out.println("result: " + ee);
        System.out.println("result: " + cc);
        
        // floor and ceil:
        double dd = 3.9;
        System.out.println("result: " + Math.floor(dd));
        System.out.println("result: " + Math.ceil(dd));
        
        double zz = 3.5;
        // can't assign a double to an int:
        // int yy = zz;
        // one possibility, use an int cast:
        int yy = (int)zz;
        System.out.println("yy: " + yy);
        // or round to a "long":
        long xx = Math.round(zz);
        System.out.println("xx: " + xx);
        
        // integer division:
        int pp = 5/2;
        System.out.println("pp: " + pp);
        // avoiding integer division:
        double rr = 5./2;
        System.out.println("rr: " + rr);
        rr = (double)5/2;
        System.out.println("rr: " + rr);
        
    }
    public static void main(String[] args)
    {   // numbers have ranges in which they're valid
        int n = 1000000;
        //System.out.println(n * n);
        
        // roundoff error can occur with doubles
        double f = 4.35;
        //System.out.println(f * 100);
        
        // declaring constants
        final int DAYS_IN_WEEK = 7;
        // error:
        //DAYS_IN_WEEK = 8;
        //System.out.println("DAYS_IN_WEEK: " + DAYS_IN_WEEK);
        //System.out.println("Java's value for Pi: (a constant) " + Math.PI);
        
        Ch4 c = new Ch4();
        //c.doMath();
        //c.workWithStrings();
        c.readInput();
        
        
    }
}