Java第六次作业
1.使用for循环计算1-100的和，除了以3结尾的那些数
package Homework;
public class H1 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int sum=0;
for(int i=1;i<=100;i++){
if(i%10!=3)
sum+=i;
}
System.out.println(sum);
}
}
2.使用二重循环输出以下图形
*
***
*****
*******
*****
****
***
**
*
package Homework;
public class H2 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
for (int i = 1; i <= 4; i++) {
for (int j = 1; j <= 4 - i; j++) {
System.out.print(" ");
}
for (int k = 1; k <= 2 * i - 1; k++) {
System.out.print("*");
}
System.out.println();
}
System.out.println();
System.out.println();
System.out.println();
System.out.println();
for (int i = 1; i <= 5; i++) {
for (int j = 1; j <= 6 - i; j++) {
System.out.print("*");
}
System.out.println();
}
}
}
3.循环输入学生姓名，直到输入‘Q’程序结束
package Homework;
import java.util.Scanner;
public class H3 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
while (true) {
System.out.println("输入学生姓名");
String a = input.next();
if (a.equals("Q")) {
System.out.println("输入的名字有效");
break;
} else
System.out.println("输入的名字无效,请重新输入");
}
}
}
4.输入5个学生成绩，求和，当输入不合法的时候，提示输入错误重新输入。
package Homework;
import java.util.Scanner;
public class H4 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
System.out.println("输入学生成绩");
int sum = 0;
for (int i = 1; i <= 5; i++) {
int grade = input.nextInt();
while (grade < 0 || grade > 100) {
System.out.println("输入的成绩无效，重新输入");
grade = input.nextInt();
break;
}
sum += grade;
}
System.out.println(sum);
}
}
5.计算 1+ 1/(1+2)+ 1/(1+2+3)+ 1/(1+2+3+4) +…………+1/(1+2+....+10)
package Homework;
public class H5 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
double sum = 0;
double j = 0;
for (int i = 1; i <= 10; i++) {
sum += i;
j = 1 / sum + j;
}
System.out.println(j);
}
}
作业
1.产生一个1-99的随机数，猜数字，若大了就提示“大了点”，若小了就提示“小了点”直到猜对位置
package Homework;
import java.util.Scanner;
public class H6 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
int number = (int) (Math.random() * 100);
System.out.println("我这里有一个0到99之间的整数，你猜是多少？");
int a = 0;
do {
int b = input.nextInt();
if (b < number) {
System.out.println("小了点!");
a++;
} else if (b > number) {
System.out.println("大了点！");
a++;
} else {
System.out.println("猜对啦!");
a++;
break;
}
} while (true);
System.out.println("这个数字是" + number);
System.out.println("您猜的次数是" + a);
if (a >= 1 && a <= 3) {
System.out.println("太棒了!");
} else if (a >= 5 && a <= 8) {
System.out.println("一般般!");
} else {
System.out.println("太笨了!");
}
}
}
2.输入一个数，判断是不是质数（只能被1和自身整除的数是质数）
package Homework;
import java.util.Scanner;
public class H7 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
System.out.println("输入一个数");
int num = input.nextInt();
boolean isPrime = true;
if (num == 1) {
isPrime = false;
}
for (int i = 2; i <= num - 1; i++) {
if (num % i == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
System.out.println(num + "是质数");
} else {
System.out.println(num + "不是质数");
}
}
}
3.求裴波那契数列的第20项是什么。裴波那契数列，1,1,2,3,5,8,13，21……\
package Homework;
public class H9 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int a=1,b=1,c=0;
for(int i=1;i<=18;i++){
c=a+b;
a=b;
b=c;
System.out.println(c);
}
System.out.println("所以这个数列第20项是:"+c);
}
}
