java程序设计基础_陈国君版第五版_第四章习题

java程序设计基础_陈国君版第五版_第四章习题

import java.util.Scanner;	
public class Main4_1 {
	public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);
		
		float testScore ;
		char grade ;
		do{
			System.out.println("请输入成绩：");
			testScore = scanner.nextFloat();
		}while((testScore<0)||(testScore>100));
		switch((int)testScore/10){
		case 10 : 
		case 9 : grade = 'A'; break;
		case 8 : grade = 'B'; break;
		case 7 : grade = 'C'; break;
		case 6 : grade = 'D'; break;
		default: grade = 'E'; break;
		}
		System.out.println("本次成绩："+testScore+"\t获得的等级是："+grade);
	}
}

import java.util.Scanner;
public class Main4_2{
	public static void main(String[] args){
		Scanner scanner = new Scanner(System.in);
		System.out.print("请输入学生的成绩：");
		float testScore = scanner.nextFloat();
		char grade;
		switch((int)testScore/10){
			case 10:
			case 9 : grade = 'A';break;
			case 8 : if(testScore>=85){grade = 'A';break;}
				 else{grade = 'B';break;}
			case 7 : grade = 'B';break;
			case 6 : grade = 'C';break;
			default: grade = 'D';break;
		}
		System.out.println("成绩"+testScore+"的等级是： "+grade);
	}
}

public class Main4_3{
	public static void main(String[] args){
		for(int i = 1;i<100;i++){
			if(i%21==0){
				System.out.println(i+"\t");
			}
		}
	}
}

import java.io.*;
public class Main4_4{
	public static void main(String[] args)throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("请输入一个数：");
		String str = buf.readLine();
		int n = Integer.parseInt(str);
		int sum = 0 ;
		for(int i = 1;i<=n;i++){
			int s = 1;
			for(int j = 1 ; j<=i;j++){
				s = s*j;
			}
			sum += s;
		}
		System.out.println("结果为："+sum);
	}
}

import java.util.Scanner;
public class Main4_5{
	public static void main(String[] args){
		float sum = 0;
		Scanner scanner = new Scanner(System.in);
		System.out.println("请输入一个数 n：");
		int n = scanner.nextInt();
		for(int i = 1;i<=n;i++){
			int s =1;
			for(int j = 1;j <= i ; j++){
				s = s*j;
			}
			sum += Math.pow(-1,i-1)/(float)s;
		}
		System.out.println("sum = "+sum);
	}
}

public class Main4_6{
	public static void main(String[] args){
		int flag = 0;
		for(int i = 100; i < 1000; i++){
			int num1 = i%10;
			int num2 = (i%100)/10;
			int num3 = i/100;
			if(i==(Math.pow(num1,3)+Math.pow(num2,3)+Math.pow(num3,3))){
				System.out.print(i+"\t");
				flag++;
			}
			if(flag >10){
				System.out.println();
				flag = 0;
			}
		}
	}
}

import java.io.*;
public class Main4_7{
	public static void main(String[] args)throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		String str ;
		System.out.println("请输入一个数:");
		str = buf.readLine();
		int n = Integer.parseInt(str);
		int sum = 0;
		for(int i = 1 ;i < n ; i++){
			if(n%i==0){
				sum += i;
			}
		}
		if(sum == n){
			System.out.println(n+"是一个完全数！");
		}else
			System.out.println(n+"不是一个完全数！");
	}
}

import java.io.*;
public class Main4_8{
	public static void main(String[] args)throws IOException{
		BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("请输入一个整数：");
		String str = buf.readLine();
		int n = Integer.parseInt(str);
		System.out.print(n+"的各位数字之和为");	
		int flag =1;
		while((n/(int)(Math.pow(10,flag)))!=0){
		  flag++;	
		}
		while(flag!=0){
			System.out.print((int)(n/(Math.pow(10,flag-1))));
			n %= Math.pow(10,flag-1);
			flag--;
			if(flag!=0){
				System.out.print("+");
			}
		}
	}
}

import java.util.Scanner;
public class Main4_9{
	public static void main(String[] args){
		Scanner scanner = new  Scanner(System.in);
		System.out.println("请输入一个浮点型数：");
		float n = scanner.nextFloat();
		System.out.println(n+"的整数部分为"+(int)n);
		System.out.println(n+"的小数部分为"+(n-(int)n));
	}
}

public class Main4_10{
	public static void main(String[] args){
		float length = 3000;
		int num = 0;
		do{
			length /= 2;
			num++;
		}while(length>=5);
		System.out.println("需要"+num+"天，绳子的长度会短于5米");
	}
}

public class Main4_11{
	public static void main(String[] args){	
		int n = 5,i=0,j,z;
		int [][] a = new int [n][n];	
		a[0][0] = 1;
		for(z = 1 ; z<n;z++){            //z判断有多少行
			j=0; 
			i = z;                       //哪行开始
			a[i][j]=a[j][i-1]+1;
			do{	                            //斜向上走 赋值
				a[i-1][j+1]=a[i][j]+1;
				i--;
				j++;
			}while(j!=z);
		}
		for(i=0;i<n;i++){
			for(j=0;j<(5-i);j++)
				System.out.print(a[i][j]+"\t");
			System.out.println();
		}
	}
}

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原文链接：java程序设计基础_陈国君版第五版_第四章习题，转载请注明来源！