Reading a program file and counting the number of comments in that file based off characters-CodePudding

I'm trying to create a program that takes a file as an input and then counts the number of comments in that file. I've created a switch case to do so.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws FileNotFoundException {

        String file = new Scanner(new
                File("file")).useDelimiter("\\Z").next();

        int length, state, i, j;
        state = 0;
        i = 0;
        j = 0;

        while (i < file.length()) {
            switch (state) {
                case 0:
                    if (file.charAt(i) == '/') {
                        state = 1;
                        i  ;
                    } else i  ;
                    break;
                case 1:
                    if (file.charAt(i) == '*') {
                        state = 2;
                        i  ;
                    } else i  ;
                    break;
                case 2:
                    if (file.charAt(i) == '*') {
                        state = 3;
                        i  ;
                    } else i  ;
                    break;
                case 3:
                    if (file.charAt(i) == '/') {
                        state = 4;
                        i  ;
                        j  ;
                    } else {
                        state = 2;
                        i  ;
                    }
                    break;
                case 4:
                    i  ;
                    break;

                default:
                    String nothing = "nothing";
            }



        }
        System.out.println("Number of comments "   j);


    }

The issue here is that it works up to 1 comment in the code. For example, if no comments exist the output would be:

#include <stdio.h>
int main()
{
   int marks, i, num;
}

Number of comments: 0

If 1 exists:

#include <stdio.h>
int main()
{
   /* comment */
   int marks, i, num;
}

Number of comments: 1

If 2 exist:

#include <stdio.h>
int main()
{
   /* comment */
   /* comment 2 */
   int marks, i, num;
}

Number of comments: 1

The issue being that it seems to be exiting my switch case as soon as it finds the first one. Is there a way to cycle this case back into the loop and start it all over again?

CodePudding user response：

The issue with your approach is when the state is set to 4 ... which is when a comment block is detected. Instead, you should replace state = 4 with state = 0 in block of case 3.

CodePudding user response：

After counting the first comment, your code is missing that state resetting logic in case 4.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws FileNotFoundException {

        String file = new Scanner(new
                File("file")).useDelimiter("\\Z").next();

        int length, state, i, j;
        state = 0;
        i = 0;
        j = 0;

        while (i < file.length()) {
            switch (state) {
                case 0:
                    if (file.charAt(i) == '/') {
                        state = 1;
                        i  ;
                    } else i  ;
                    break;
                case 1:
                    if (file.charAt(i) == '*') {
                        state = 2;
                        i  ;
                    } else i  ;
                    break;
                case 2:
                    if (file.charAt(i) == '*') {
                        state = 3;
                        i  ;
                    } else i  ;
                    break;
                case 3:
                    if (file.charAt(i) == '/') {
                        state = 4;
                        i  ;
                        j  ;
                    } else {
                        state = 2;
                        i  ;
                    }
                    break;
                case 4:
                    i  ;
                    state = 0;
                    break;

                default:
                    String nothing = "nothing";
            }



        }
        System.out.println("Number of comments "   j);


    }