Question

I’m trying to write a program that gets a .txt file that only has something like 10000010000010000010001

I’m trying to count the number of zeros and output it like 5 5 5 3. I thought if I convert a string into a double or int I could write an if or for loop.

import java.util.Scanner;

public class test1{

    public static void main(String[] args) {

        java.io.File test2 = new java.io.File("test3.txt");

        try
        {
           Scanner input = new Scanner(test2);

        while(input.hasNext())
        {
            String num = input.nextLine();
            System.out.println(num);

            double n = Double.parseDouble(num);
            System.out.println(n);
        } 
        }

        catch (Exception e){
            System.out.println("could not find file");
        }   

       }

}

Answer 1

Here you go:

char[] numArray = num.toCharArray();
  int counter=0;
  for(int i=0;i<numArray.length;i++) {
     if(numArray[i]=='0') {
        counter++; 
     }
     if((i==numArray.length-1&&counter>0)||(counter>0&&numArray[i]!='0')) {
        System.out.println("Number of Zeroes: "+counter);
        counter=0;
     }
  }

Some important points:

1) It’s best to use an array of char values here, instead of operating using a double, because a char array can store many more values- the example you posted is too long for a double to handle.

2) Most of this should be self-explanatory (at least, if you study it bit-by-bit), but in case the i==numArray.length-1 part is confusing, this ensures that if the string ends with a 0, the final count of 0’s will be printed out as well.

This should work for any string you can throw at it- including values besides 0 and 1, if you need support for it!