Simple Array Insertion Program Producing Incorrect Output

Question

Here's an extremely simple java program where I declare any array with 7 elements, input the first six, move the fourth to sixth elements to the fifth to seventh positions, and obtain a value for the fourth empty position:

int A[]=new int[7];
        for(int i=0;i<6;i++)
        {
            System.out.println("Enter an integer");
            String a=Biff.readLine();
            A[i]=Integer.parseInt(a);
        }
        for(int i=4;i<6;i++)
        {
            A[i]=A[i+1];
        }
        System.out.println("Enter the integer to be inserted");
        String a=Biff.readLine();
        A[4]=Integer.parseInt(a);

However, when all array elements are printed, the sixth and seventh positions are 0, and I have no idea why. Reasons and fixes will be greatly appreciated. Note: I can't use any array methods, have to keep it very simple.

Input: 1,2,3,4,5,6; Then 1;
Desired Output: 1,2,3,4,5,1,6;
Actual Output: 1,2,3,4,1,0,0;

*"the sixth and seventh positions are 0*" What are you *expecting* them to be? Show your input, output, and *expected* output, and highlight the difference for us. — T.J. Crowder, Jul 10 '16 at 13:03

score 5 · Accepted Answer · edited Jul 10 '16 at 13:06

5

Your initial loop is not assigning anything to the 7th element, so it remains 0.

And later you copy the 7th element to the 6th one

 A[i]=A[i+1];

so both the 6th and 7th elements should be 0.

Change the loop to :

    for(int i=0;i<A.length;i++)
    { //         ^^^^^^^^^------------------------ change is here
        System.out.println("Enter an integer");
        String a=Biff.readLine();
        A[i]=Integer.parseInt(a);
    }

edited Jul 10 '16 at 13:06

Peter Lawrey

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answered Jul 10 '16 at 13:03

Eran

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@PeterLawrey No problem :) – Eran Jul 10 '16 at 13:07
Ah, ok, but I can't use .length(), how would I fix it then? – Aryan poonacha Jul 10 '16 at 13:12
@Aryanpoonacha You can always use 7 instead of length, but length makes much more sense. – Eran Jul 10 '16 at 13:16

score 0 · Answer 2 · answered Jul 10 '16 at 13:09

0

You are moving the values in the wrong way. Use this code and understand your mistake:

for(int i=6;i>=3;i--)    //Moving the 4th to 6th elements to 5th to 7th elements
    {
        A[i]=A[i-1];
    }
String a=Biff.readLine();    //Taking input for 4th empty position
A[3]=Integer.parseInt(a);

I hope I got your question right.

answered Jul 10 '16 at 13:09

VatsalSura

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Tried that, but it still makes the seventh position have a value of 0. – Aryan poonacha Jul 10 '16 at 13:16
It will only happen if you input 6th value 0, then and only the 7th value will be 0 as we are copying 6th value directly in 7th value. Check again. – VatsalSura Jul 10 '16 at 13:18

Simple Array Insertion Program Producing Incorrect Output

2 Answers2