2013-10-16 作业

1.写代码实现从控制台接受一个char类型字符，并且输出

import java.io.*;
import java.util.Scanner;
public class total {
 public static void main (String args[]) throws IOException{
  String mystring;
 
  BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));
  System.out.println("input a bufferReader string");
  mystring=buf.readLine();
  System.out.println("bufferReader string="+mystring);
 
   Scanner scannerstring=new Scanner(System.in);
   System.out.println("input a scanner string");
   mystring=scannerstring.next();
   System.out.println("scanner string="+mystring);
  }
}

更正：根据题意将代码调整为：

import java.io.*;
import java.util.Scanner;
public class total {
 public static void main (String args[]) throws IOException{
   char c = (char)System.in.read();
    System.out.println("c="+c);
  }
}

2.打印

public class print{
 public static void main(String args[]){
  for(int i=1;i<=5;i++){  
   for(int j=1;j<=2*i-1;j++){
   System.out.print("*");
      }
   System.out.println(" ");
  }
 }  
}

3、求1-1/2+1/3-1/4+…+1/99-1/100的和

import java.lang.Math;
public class math{
 
 public static void main(String args[]){
  double sum=0;
 for(int i=1;i<=100;i++){
  sum=sum+Math.pow(-1,i+1)*1/i; 
 }
 System.out.println("1-1/2+1/3+...+1/99-1/100="+sum);  
 } 
}