Java程序③分別用do-while和for循環計算1+1/2!+1/3!+…前20項和

大二軟件工程學生，初學Java，小小小小程序，練個手。想認識新朋友。☀☀☀

 

do-while

/**
 * 用do-while計算1+1/2！+1/3！+……的前20項的和
 * @author Rigel
 *
 */
public class Add2 {

	public static void main(String[] args) {
		int  i = 1, a = 1;
		double sum = 0,b = 0;
		do {
			a = i * a;
			b = 1.0 / a;
			sum = sum + b;
			i++;
		}while(i <= 20);
		
		System.out.println(sum);
	}

}

for循環

/**
 * 用for循環計算1+1/2！+1/3！+……的前20項的和
 * @author Rigel
 *
 */
public class Add1 {

	public static void main(String[] args) {
		int  i = 1, a = 1;
		double sum = 0,b = 0;
		for(i = 1; i <= 20; i++) {
			a = i * a;
			b = 1.0 / a;
			sum = sum + b;
		}
		System.out.println(sum);
	}

}