06.データタイプ

/**
 *
 */
package lesson03;

/**
 * @author gridscale
 *
 */
public class Calculator {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		//
		// 2 ** 15 + ..... + 2*1 + 1 = ?
        // 16 BIT整数の最大値を計算
		long sum = 0;
		sum = maxvalueOfBinary(16);

		System.out.println("Sum of 2**15 + ... + 2**1 + 1 = " + sum );

		sum = maxvalueOfBinary(20);
		System.out.println("Max value of 20 bits is:" + sum);

		// 32 BIT整数の最大値を計算
		sum = maxvalueOfBinary(32);
		System.out.println("Sum of 2**31 + ... + 2**1 + 1 = " + sum);

		System.out.println("Max vaue of Integer is: " + Integer.MAX_VALUE);
		System.out.println("Min value of Integer is: " + Integer.MIN_VALUE);
        // int -> Integer Class
	}

	/**
	 *
	 * @param numberOfBits
	 * @return
	 */
	public static long maxvalueOfBinary(int numberOfBits) {
		long sum = 0;
		for (int i = numberOfBits-1; i >=0 ; i--) {
			sum += powerOf2(i);
		}
		return sum;
	}

	/**
	 * 2のN次乗
	 *
	 * @param n
	 * @return
	 */
	public static long powerOf2(int n) {

		long power = 1;
		for (int i = 0; i < n; i++) {
			power *= 2;
		}

		//TODO
		// n = 0 -> 1;
		// n = 1 -> 2;
		// n = 2 -> 4;

		return power;
	}

}