CODEWITHSUNDEEP
java
Kenlucius
Kenlucius

Reputation: 141

What is the cause of this infinite loop?

I have a problem. I am trying to use a for loop to run a PI approximation. The following is my code (From after main). Why does this loop never terminate?

System.out.println("Start"); 
    double sum1 = 1.0, sum2 = 1.0;
    int j =1;
    for(int i=1;i<6;i++)
    {
        if((j/2)!=0)
            i = i*-1;
        if(i>5)
        {
            sum1 += 0;
        }
        else
        {
            sum1 += ((double)1.0/(i+2.0));
            sum2 += ((double)1.0/(i+2.0));
        }
        j++;
    }
    System.out.println("PI 1 = " + 4*sum1);
    System.out.println("PI 2 = " + 4*sum2);

Upvotes: 0

Views: 64

Answers (1)

b4hand
b4hand

Reputation: 9770

Because you modify i inside of your loop to be negative when j is greater than or equal to 2, you can't guarantee the loop terminates.

In fact, i continuously oscillates between a positive and negative number on successive iterations after j >= 2.

Upvotes: 2

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