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I wrote a perfect number program, but when I run it, it outputs that every number is perfect. Please help me find my mistake.

This is my server code:

public class Perfect
{
   private int number;

    public Perfect()
    {
        number = 0;
    }

    public Perfect(int num)
    {
        number = num;
    }

    public void setPerfect(int num)
    {
        number = num;
    }

    public boolean isPerfect()
    {
        int number = 0;
        int div = 0;
        int num = 1;
        while (num < number)
        {
            if (number % num == 0)
            {
                div += num;
            }
            num++;
        }

        if ( div == number)
            return true;

        else    
            return false;
    }

   public String toString()
    {
        if (isPerfect() == true)
          return number + " is perfect";
        else
          return number + " is not perfect";
    }
}

And the output I got was every number I typed in is perfect.

false
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user2817151
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4 Answers4

4

in isPerfect you have defined a local variable number = 0. This is the value being tested instead of the field number. The local variable is hiding the class field.

John B
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2

I think your problem is here:

public boolean isPerfect() {
    int number = 0;
    ...

You should probably be using the object's field number instead of shadowing it with a new variable initialized to zero.

kviiri
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1

The line int number = 0; inside the isPerfect function is the cause of your trouble.

abiessu
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0

You have 

int number = 0;
int num = 1;
while (num < number)
{
...
}

which tests for 

while (1 < 0)

So the loop never runs. Next you have 

int div = 0;
if ( div == number)

which tests for 

if (0 == 0)
    return true;

Therefor every number is perfect.

Olaf Dietsche
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