Java how to program(第六版)第五章

1、第五章 控制语句（第部分）5.5 计数控制器的4个所需要素为：1）一个控制器2）控制器的初始值3）用于修改控制变量的增量或减量4）循环继续条件5.6 while是先判断后执行，如果条件不满足，则一次循环体语句也不执行。for(表达式1;表达式2;表达式3) 第一步，计算表达式1的值。第二步，计算表达式2的值。若值为真(非0)则执行循环体一次，否则跳出循环。第三步，计算表达式3的值，转回第二步重复执行5.7 dowhile和while的区别就是前者至少执行一次，也就是对于至少执行一次的程序使用前者很好。两种循环基本没有区别。5.8 break是结束循环 continue是结束本次循环。就是这么简

2、单。具体的相见书本。5.9 a)逗号应该为分号，修改后为：for ( i=100; i=1; i+ )System.out.println(i);b)如果为偶数是会出现：Even integer Odd integer如果奇数会：Odd integer修改后为：switch ( value % 2 )case 0:System.out.print(Even integer);break;case 1:System.out.println(Odd integer);break;c)自增条件错误，修改后的程序为：for ( i=19; i=1; i-=2 )System.out.println(i

3、);d)判断的条件错误，修改后的程序为：counter = 2;doSystem.out.println(counter);counter += 2;while ( counter = 100 );5.10程序输出结果如下，即可看出：5.11程序代码为：import java.util.Scanner;public class Exercise1 /* * param args */public static void main(String args) / TODO Auto-generated method stubScanner input = new Scanner(System.in

4、);int min;int number;int n;int i = 1;System.out.println(Enter the number you want to input:);n = input.nextInt();System.out.printf(Enter %d numbers:n, n);number = input.nextInt();min = number;while ( i n )number = input.nextInt();if ( number min )min = number;i+;System.out.printf(The minimum number

5、is %d!, min);5.12程序代码如下：public class Exercise2 /* * param args */public static void main(String args) / TODO Auto-generated method stubint n = 1;int i;for ( i=1; i=15; i+=2 )n *= i;System.out.printf(The mutiplication is :%d, n);5.13程序代码为：public class Exercise2 /* * param args */public static void ma

6、in(String args) / TODO Auto-generated method stubint factorial = 1;int n;System.out.printf(%-5s%10sn,N,Factorial);for ( n=1; n=5; n+ )factorial *= n;System.out.printf(%-5d%-10dn, n, factorial);不能求20的阶乘是因为int型的存储有限，20的阶乘超过了存储的最大值。5.14修改后的程序为：public class Interest public static void main( String args

7、) double amount; / amount on deposit at end of each year double principal = 1000.0; / initial amount before interest double rate; / interest rate / display headers System.out.printf( %s%20sn, Year, Amount on deposit ); for ( rate=5; rate=9; rate+ ) rate /= 100; / calculate amount on deposit for each

8、 of ten years for ( int year = 1; year = 10; year+ ) / calculate new amount for specified year amount = principal * Math.pow( 1.0 + rate, year ); / display the year and the amount System.out.printf( %4d%,20.2fn, year, amount ); / end for / end main / end class Interest5.15a)程序代码为：public class Exerci

9、se2 /* * param args */public static void main(String args) / TODO Auto-generated method stubint i;int j;int n = 10;for ( i=1; i=n; i+ )for ( j=1; j=1; i- )for ( j=1; j=1; i- )for ( j=n-i; j=1; j- )System.out.print( );for ( j=1; j=i; j+ )System.out.print(*);System.out.println();d)程序代码为：public class E

10、xercise2 /* * param args */public static void main(String args) / TODO Auto-generated method stubint i;int j;int n = 10;for ( i=1; i=1; j- )System.out.print( );for ( j=1; j=i; j+ )System.out.print(*);System.out.println();5.16程序代码为：import java.util.Scanner;public class Exercise2 /* * param args */pub

11、lic static void main(String args) / TODO Auto-generated method stubScanner input = new Scanner(System.in);int i = 1;int j;int n = 5;int number;System.out.println(Enter 5 numbers between 1 and 30!);System.out.printf(Enter the %dth number :, i);number = input.nextInt();for ( j=1; j=number; j+ )System.

12、out.print(*);System.out.println();while ( i = n-1 )System.out.printf(Enter the %dth number :, i+1);number = input.nextInt();for ( j=1; j=number; j+ )System.out.print(*);System.out.println();i+;5.17程序代码为：import java.util.Scanner;public class Market private double price;private int serialNumber;privat

13、e int productAmount;private double amountMoney = 0.0;public double productPrice( int serialNumber )switch ( serialNumber )case 1:price = 2.98;break;case 2:price = 4.50;break;case 3:price = 9.98;break;case 4:price = 4.49;break;case 5:price = 6.87;break;return price;public void displayMessage()Scanner

14、 input = new Scanner( System.in );int number = 1;System.out.printf(Enter the serial number and sale of the product:);serialNumber = input.nextInt();productAmount = input.nextInt();amountMoney += productAmount*productPrice(serialNumber);while ( number 5 )System.out.printf(Enter the serial number and

15、sale of the product:);serialNumber = input.nextInt();productAmount = input.nextInt();amountMoney += productAmount*productPrice(serialNumber);number+;System.out.printf(The total sale money is %.3f, amountMoney);测试如下：public class MarketTest /* * param args */public static void main(String args) / TODO

16、 Auto-generated method stubMarket market = new Market();market.displayMessage();5.18程序与原程序基本无差别，在这儿就不写出了。5.19 a)显示：true b)显示：false c)显示：true d)显示：false e)显示：true f)显示：false g)显示：false5.20程序如下：public class Exercise1_1 /* * param args */public static void main(String args) / TODO Auto-generated method

17、 stubint n = 3;int i;int sign = 1;double pi = 0.0;System.out.printf(%s%10sn,Item Number,PI);for ( i=1; i=(2*n-1); i+=2 )pi += 1.0*sign/i;sign = -sign;System.out.printf(%d%10.3fn, (i+1)/2, pi*4);对于估算，可以试着来，也可以用程序设计用。这儿就不在赘述。5.21程序代码为：public class Exercise1_1 /* * param args */public static void main(

18、String args) / TODO Auto-generated method stubint side1;int side2;int hypotenuse; System.out.printf(%s%10s%10sn,side1,side2,hypotenuse); for ( hypotenuse=1; hypotenuse=500; hypotenuse+ ) for ( side1=1; side1hypotenuse; side1+ ) for ( side2=1; side2side1; side2+ ) if ( hypotenuse*hypotenuse = side1*s

19、ide1+side2*side2) System.out.printf(%d%10d%10dn, side1, side2, hypotenuse); 5.22程序代码为：public class Exercise1_1 /* * param args */public static void main(String args) / TODO Auto-generated method stubint i;int j;int n = 10;for ( i=1; i=n; i+ )for ( j=1; j=i; j- )System.out.print( );for ( j=n-i+1; j=1

20、; j- )System.out.print(*);for ( j=1; j=1; j- )System.out.print(*);for ( j=n+5; j=i; j- )System.out.print( );for ( j=1; j=i; j+ )System.out.print(*);System.out.println();5.23程序按照要求容易写，故不再赘述。5.24程序代码为：public class Exercise1_2 /* * param args */public static void main(String args) / TODO Auto-generated

21、 method stubint i;int j;int n =5;for ( i=1; i=n; i+ )for ( j=1; j=n-i; j+ )System.out.print( );for ( j=1; j=1; i- )for ( j=1; j=n-i; j+ )System.out.print( );for ( j=1; j=(2*i-1); j+ )System.out.print(*);System.out.println();5.25程序代码为：import java.util.Scanner;public class Exercise1_2 /* * param args

22、*/public static void main(String args) / TODO Auto-generated method stubScanner input = new Scanner( System.in );int i;int j;int n;System.out.println(Enter a odd number between 1 and 19:);n =input.nextInt();System.out.println(The graph is :);for ( i=1; i=n; i+ )for ( j=1; j=n-i; j+ )System.out.print

23、( );for ( j=1; j=1; i- )for ( j=1; j=n-i; j+ )System.out.print( );for ( j=1; j=(2*i-1); j+ )System.out.print(*);System.out.println();5.26程序为：public class BreakTest public static void main( String args ) int count; / control variable also used after loop terminates for ( count = 1; count = 10; count+

24、 ) / loop 10 times if ( count 5 ) / if count is 5, System.out.printf( %d , count ); / terminate loop / end for System.out.printf( nBroke out of loop at count = %dn, (count+1)/3 ); / end main / end class BreakTest5.27程序结果为：*5.28修改后的程序为：public class ContinueTest public static void main( String args )

25、for ( int count = 1; count 2) display(-x); public static void main(String args) Christmas c=new Christmas(); for(int i=1;i=12;i+) switch(i) case 1: System.out.println(On the first day of Christmasnmy true love sent to me:); c.display(i); break; case 2: System.out.println(On the second day of Christmasnmy true love sent to me:); c.display(i); break; case 3: System.out.println(On the third day of Christmasnmy true love sent to me:); c.display(i); break; case 4: System.out.println(On the foruth day of Christmasnmy true love sent to me:); c.display(i); break; case 5: System.out.println(