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London | 26-Java-June | Fatma Arslantas | Sprint 1 | Reverse Numbers #21

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London | 26-Java-June | Fatma Arslantas | Sprint 1 | Reverse Numbers #21

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6 changes: 6 additions & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
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# IntelliJ IDEA
.idea/
*.iml

# Java build output
out/
28 changes: 28 additions & 0 deletions src/ReverseNumbers.java
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public class ReverseNumbers {
public static void main(String[] args) {
int originalNumber = 3956;
int reversedNumber = reverseNumber(originalNumber);

System.out.println("Original number: " + originalNumber);
System.out.println("Reversed number: " + reversedNumber);
}

/**

@jabeywick jabeywick Jul 3, 2026

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Nice javadoc!

@AFatmaa AFatmaa Jul 4, 2026

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Thank you!

* Reverses the digits of a positive integer.
*
* @param number the number to reverse
* @return the number with its digits in reverse order
*/
private static int reverseNumber(int number) {
int reversedNumber = 0;
int remaningNumber = number;

while (remaningNumber > 0) {

@jabeywick jabeywick Jul 3, 2026

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What changes would you have to make to get this working for negative numbers?

@AFatmaa AFatmaa Jul 4, 2026

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To support negative numbers, I would handle the sign separately.

The current loop only works for positive numbers because it runs while remainingNumber > 0. For a negative number, I would first check whether the original number is negative, then reverse the absolute value of the number, and finally return the result as negative again if needed.

I could update the method like this:

private static int reverseNumber(int number) {
    boolean isNegative = number < 0;
    int remainingNumber = Math.abs(number);
    int reversedNumber = 0;

    while (remainingNumber > 0) {
        int digit = remainingNumber % 10;
        reversedNumber = reversedNumber * 10 + digit;
        remainingNumber = remainingNumber / 10;
    }

    if (isNegative) {
        return -reversedNumber;
    }

    return reversedNumber;
}

For example, -3956 would return -6593.

Would this be a good way to handle negative numbers?

@jabeywick jabeywick Jul 10, 2026

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Yep nice one - this looks good to me!!

int digit = remaningNumber % 10;

@jabeywick jabeywick Jul 3, 2026

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This looks great 😄

@AFatmaa AFatmaa Jul 4, 2026

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Thank you!

reversedNumber = reversedNumber * 10 + digit;
remaningNumber = remaningNumber / 10;
}

return reversedNumber;
}
}