java程序设计基础_陈国君版第五版_第四章例题

java程序设计基础_陈国君版第五版_第四章例题

<pre name="code" class="java">public class Main4_1 {public static void main(String[] args){int a = 1,b = 2,c = 3,max,min;if(a>b)max = a;elsemax = b;if(c>max) max = c;System.out.println("Max = "+max);min = a<b?a:b;min = c<min?c:min;System.out.println("Min = "+min);}}

public class Main4_2 {public static void main(String[] args){int testScore = 86;char grade;if(testScore>=90){grade='A';}else if(testScore>=80){grade='B';}else if(testScore>=70){grade='C';}else if(testScore>=60){grade='D';}else{grade='E';}System.out.println("评定成绩为："+grade);}}

public class Main4_3 {public static void main(String[] args)throws Exception{int a=100,b=6;char oper;System.out.print("请输入运算符：");oper = (char)System.in.read();switch(oper){case '+':System.out.println(a+" + "+b+" = "+(a+b));break;case '-':System.out.println(a+" - "+b+" = "+(a-b));break;case '*':System.out.println(a+" * "+b+" = "+(a*b));break;case '/':System.out.println(a+" / "+b+" = "+((float)a/b));break;default:System.out.println("输入的符号不正确！/");}}}

import java.util.Scanner;public class Main4_4 {public static void main(String[] args){Scanner scanner = new Scanner(System.in);int month,days;System.out.print("请输入月份：");month = scanner.nextInt();switch(month){case 2:days = 28;break;case 4:case 6:case 9:case 11: days =30;break;default:days = 31;}System.out.println(month+"月份为"+days+"天");}}

public class Main4_5 {public static void main(String[] args){final int MAX = 16;int i=0,j=1,k=0;   //i为第n-1项，j为第n项，n>=1且n<16,k计数；此时为输出任何所以k=0；while(k<MAX){System.out.print(" "+i+" "+j);i = i+j;j = j+i;k = k+2;}}}

import java.io.*;public class Main4_6 {public static void main(String[] args)throws IOException{BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));String str = buf.readLine();int num = Integer.parseInt(str);int i=0,j=1;while(j<num){i = i+j;j = j+i;}if((i==num)||(j==num)){System.out.println(num+"是fibonacci数！");}else{System.out.println(num+"不是斐波那契数！");}}}

import java.util.Scanner;public class Main4_7 {public static void main(String[] args){double sum = 0;int n =0;Scanner scanner = new Scanner(System.in);while(scanner.hasNextDouble()){sum += scanner.nextDouble();n++;}System.out.println(n+"次加法的和是"+sum);}}

import java.io.*;public class Main4_8 {public static void main(String[] args)throws IOException{BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));int n;int num = 0,i=1;do{System.out.println("请输入一个正整数：");String str = buf.readLine();n = Integer.parseInt(str);}while(n<=0);while(i<=n){num+=i;i++;}System.out.println(num);}}

import java.util.Scanner;public class Main4_9 {public static void main(String[] args){Scanner scanner = new Scanner(System.in);int a,b,k;System.out.println("请输入a = ");a=scanner.nextInt();System.out.println("请输入b = ");b=scanner.nextInt();System.out.print("gcd("+a+","+b+")"+" = ");do{k = a%b;a = b;b = k;}while(k!=0);System.out.println(a);}}

import java.util.Scanner;public class Main4_10 {public static void main(String[] args){Scanner scanner = new Scanner(System.in);int M;int N = 1,S=1;do{System.out.println("请输入M：");M = scanner.nextInt();}while(M<=1);do{S = S*N;N++;}while(S<M);System.out.println("此时的S为"+(S/(N-1))+"此时的N为"+(N-2));}}

public class Man4_11 {public static void main(String[] args){int i,n = 10,s=0;for(i=1;i<=n;i++)s+=i;System.out.println("sum=1+....+"+n+"="+s);s=0;System.out.print("sum=");for(i = n ;i>1;i--){s+=i;System.out.print(i+"+");}System.out.println(i+"="+(s+i));}}

public class Main4_12 {public static void main(String[] args){final int MAX=100;int j,k,n;System.out.println("2~"+MAX+"之间所有的素数为：");System.out.print("2\t");n=1;k=3;do{j=3;while(j<Math.sqrt(k)&&(k%j!=0))j++;if(j>Math.sqrt(k)){System.out.print(k+"\t");n++;if(n%10==0) System.out.println();}k=k+2;}while(k<MAX);System.out.println("\n共有"+n+"个素数");}}