[USEFUL] Got the right answer but want to try differnt approach using FOR LOOP and isnt working

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HELP WITH FOOR LOOP Got the right answer utilizig the while loop, but want to try differnt approach and with for loop and its not working Before the continue keyword, i simply printed the output to see what was being printed... it seems only the last digit of enteredNum prints. E.g. input is : 4445 output will be : 5 5 5 5 Even: 0 Odd: 4 Here is my code:

public class Solution {

    public static int even;
    public static int odd;

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

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int enteredNum = Integer.parseInt(reader.readLine());
        int digit = 0;

//        while (enteredNum > 0) {
//            digit = enteredNum % 10;
//            if (digit % 2 == 0) {
//                even++;
//            } else if (digit % 2 != 0) {
//                odd++;
//            }
//            enteredNum /= 10;
//        }

        for (int i = enteredNum; i > 0; i /= 10) {
            digit = enteredNum % 10;
            if (enteredNum % 2 == 0) {
                even++;
            } else {
                odd++;
            }
            System.out.println(digit);
            continue;

        }
        System.out.println("Even: " + even + " Odd: " + odd);

    }
}

I was thiking perhaps with the continue key word, it would move onto the next iteraition. and then carry out the last part of the for loop condition,

i /= 10

My thinking : 1 - enteredNum (input) is 4445 2 - 4445 is larger than 0, go inside for loop 3 - in a seperate var called digit, carry ou enteredNum % 10 to get last digit 4 - use the if / else statement to determine if the digit is even or odd and add he respected counter 5 - use continue keyword to move onto next iteration 6 - take the 4445 input and now i /= 10, resulting in 444 7 - 444 > 0, go inside loop 8 - repeat process until 0 is no longer greater than 0 is there a flaw in the logic or is it a syntax issue. Thanks in advance :)

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Guadalupe Gagnon

Level 37 , Tampa, United States

1 July 2021, 13:18

First: Awesome that you are practicing solving tasks with different techniques!! Everyone learns differently, but I predict you will learn at an accelerated rate doing this. Second: Great job using the System.out.println() method to output each digit inside the loop. Doing this is one of the easiest to learn techniques of debugging. Keep doing this and as you progress you will learn where to put these statements in your code and read the output. Now, the problem: the variable enteredNum is never changed inside of the for loop the same way it is changed in the commented out while loop. This means that each loop cycle it sets "digit" to the result of enteredNum % 10 (which when the input is 4445 the result will be 5, as your println() method is showing). Either use the variable "i" instead of enteredNum, or you can get rid of i all together:

for( ; enteredNum > 0; enteredNum /= 10) {
   // rest of code
}

Usman Full Stack Developer at QA

1 July 2021, 14:02

omg haha, with regards to using “i” instead of enteredNum, thats such facepalm smh moment - how did i miss something to simple! but as for getting rid of its completely - i didn’t even know that could be implemented like that. thats really helpful. Thank you Guadalupe, and Appreciate the words of encouragement :))

Guadalupe Gagnon

Level 37 , Tampa, United States

1 July 2021, 16:10

A quick lesson, for you and anyone else that reads this in the future: A "for" loop is initialized with 3 optional statements. The only thing that is required is the 2 semi colons inside the parentheses. You can even write a for loop with no conditions, which is the same as an infinite loop. This is a valid implementation:

for( ; ; ) {
   // code in here would loop infinitely
}

The three conditions are ({1}; {2}; {3}): 1) a statement that executes prior to the start of the loop 2) a boolean expression that executes at the start of each loop cycle 3) a statement that executes at the end of each loop cycle So a loop such as:

for(int i = 0; i < 3; i++) {
   print(i);
}

is the same exact as this code:

int i = 0; // #1 before the loop
// loop cycle 1
if(i < 3) // #2 boolean expression before loop
{
   print(i); // this is code in loop
} else goto end; // goto doesn't work in Java, this is just to illustrate what a loop does
i++; // #3 expression after loop cycle

// loop cycle 2
if(i < 3) // #2
{
   print(i);
} else goto end;
i++;// #3

// cycle 3
if(i < 3) //#2
{
   print(i);
} else goto end;
i++; // #3
/*end*/

Guadalupe Gagnon

Level 37 , Tampa, United States

1 July 2021, 16:16

other acceptable implementations:

// when no middle expression it will default to 'true'
// which will be infinite
for(int i = 0; ; i++) {
}

for(int i = 0; i < 10; ) {
}

for( ;i < 10; i++) {

}

Also, compound expressions are acceptable:

for(int a = 0, b = 9; a < 10 && b >= 0; a++, b--) {

}

Usman Full Stack Developer at QA

1 July 2021, 16:42

all makes sense. compoound expressions within an for loop... thats interesting. im sure that will come useful 👍

Thomas

Level 41 , Bayreuth, Germany

1 July 2021, 13:14

the for loop is exactly the same as the while loop. The abort condition of the while loop is the middle part of the for loop. The third part of the for loop is the (abort) variable change (last line in your while loop). The first part, the initialization, you do not necessarily need but you can put the digit initialization here like:

for (int digit = 0; enteredNum > 0; enteredNum /= 10) {
    digit = enteredNum % 10;
    if (digit % 2 == 0) {
        even++;
    } else {
        odd++;
    }
}

Usman Full Stack Developer at QA

1 July 2021, 14:03

Thank you Thomas, that makes perfect sense now. i can see also what was in fact notneeded for cleaner code as well. very grateful.