Question

我试图找到pi中每个数字的出现次数（有多少1＆＃39; s，2＆＃39; s，3＆＃39; s）。我已经知道每个数字的出现次数，但是当我试图找到每个数字的百分比时，我总是得到0.这里是代码：

import java.util.*;
import java.io.*;
import java.net.*;
import java.text.DecimalFormat;

public class PIAnalyzer {

   static int digit, index;

   public static Scanner openFileURL(String website) {
      Scanner scan = null;
      try {
         URL webAddress = new URL(website);
         InputStream input = webAddress.openStream();
         System.out.println("Opened web page: " + webAddress.getPath());
         scan = new Scanner(input);
      } catch (MalformedURLException e) {
         System.out.println("Cannot open web site:");
         System.out.println(e);
      } catch (IOException io) {
         System.out.println("IO Error:" + io.toString());
      }
      return scan;
   }

   public static void main(String[] args) {
      //System.getProperties().put("http.proxyHost", "10.10.1.5");
      //System.getProperties().put("http.proxyPort", "8080");
      DecimalFormat df = new DecimalFormat("#.##");
      int[] digitCount = new int[10];
      Scanner in = openFileURL("http://www.eveandersson.com/pi/digits/1000000");
      if (in == null) {
         System.out.println("URL error");
      }
      //ignore web page fluff at the beginning; adjust the loop so this works.
      //we are displaying the lines of text to make it easier to determine if we are ignoring the correct amount.
      for (int i = 0; i < 20; i++) {
         System.out.println(in.nextLine());
      }



      String line;
      char ch;
      int index;
      //We analyze the file line by line
      int countChars = 0;
      while (in.hasNext() && countChars < 1000) {
         line = in.nextLine();
         countChars += line.length();
         System.out.println(line);
         char[] pear = line.toCharArray();
         //to look at each character, use charAt or toCharArray
         // look at each character.
         //for loop through the string.
         for (int i = 0; i < pear.length; i++) {
            ch = pear[i];
            if (Character.isDigit(ch)) {
               index = ch - '0';
               digitCount[index]++;
            }
         }


      } //end while loop through lines
      //get sum of all numbers in for loop
      int sum = 0;
      for (int a = 0; a <= digitCount.length - 1; a++) {
         sum += digitCount[a];

      }
      System.out.println("Number of total char: " + countChars);
      System.out.println("Number of char proccessed: " +sum + " //why?");

      System.out.println("Digit" + "\t" + "# occurrence" + "\t" + "% occurrence");


      for (int i = 0; i <= digitCount.length - 1; i++) {
         System.out.print(i + "\t" + digitCount[i]);
         int percentOccurence = ((digitCount[i] / sum));
         System.out.println("\t\t" + percentOccurence + "%");
      }
   }
}

Answer 1

int除以int是int。所以3/4 = 0，7/2 = 3等等。

Answer 2

更改

int percentOccurence = ((digitCount[i] / sum))

到

int percentOccurence = (100 * digitCount[i]) / sum

或者，如果您希望将百分比显示为分数，请执行浮点除法：

double percentOccurence = (double) digitCount[i] / sum

查找百分比总是等于0？

2 个答案: