我正在创建的该程序必须检查一个数字是否为另一个数字的倍数

Question

This is what I have so far. If I put in a 4 for the first number and a 6 for the second it says that 4 is a multiple of 6,which is incorrect. I am not sure what is going on with it.

    System.out.print("\n Name =");
    String userName = console.readLine();

    System.out.print("\n First Number =");
    int firstNumber = console.readInt();

    System.out.print("\n Second Number =");
    int secondNumber = console.readInt();

    if (firstNumber / secondNumber == 0 || secondNumber / firstNumber == 0) {
        System.out.print("\n" + userName + "," + firstNumber + " is a multiple of " + secondNumber);
    }
    else {
        System.out.print("\n" + userName + "," + firstNumber + " is not a multiple of " + secondNumber);
    }

Answer 1

You can easily check if a number is a multiple of an other with a modulo. Apply the module to the multiple you want to check, then simply confirm the remaining is equal to 0.

Example :

int number = 3;
System.out.println("isMultiple : " + (number % 3 == 0));

As for what is wrong in your code, you divide and check if equals to 0, this is not the correct way to do.

Look at this line

firstNumber / secondNumber == 0

Replace firstNumber with 6 and secondNumber with 3, it will return 2 which won't be equals to 0 even if 3 is a multiple of 6.

Answer 2

The simplest way to check if one number is a multiple of another is to use a modulo (remainder after division) operation. So, the code might look like:

if(firstNumber % secondNumber == 0) {
    // I'm a multiple!
}

Remember to check that secondNumber is not zero, otherwise you'll run a into division by zero!

Answer 3

Divide an int by an int give an int , so 6/4 == 0 .

You can :

• Use the module as suggested by JF Savard
• Cast first and second number into double or float , and check if the result is equals to itself casted as int (or rounded)

Answer 4

What is wrong is this check: firstNumber / secondNumber == 0 and the other one there. This is not how you correctly check if a number divides another number.