SIGSEGV Error (Probably Array Index Out Of Bound)

Question

Can anybody please help to find an error in this code? I am not able to get the error, & its giving a Runtime error. I checked all loops used for matrix but not able to find an error.

    int  n, arr[n][n];
    cin>>n;
    for (i=0; i<n; i++)
    {
        for(j=0; j<n; j++)
        {
            cin>>arr[i][j];
        }
    }

    for (i=0; i<n; i++)
    {
        for(j=0; j<n; j++)
        {
            sum = 0;
            prev = ne;
            ne = 0;

            if(arr[i][j] == 1)
            {
                ne = i+j;
                prev = i+j;
                sum = ne - prev; 
                if(sum<0)
                    sum=-sum;
                steps+=sum;
            }           
            c++;
        }
    }

I've tried with 0 indices also, its giving the same error @MartinJames — Kiran Malvi, Dec 08 '15 at 13:20
Initialize `n` to the value of your choice, initialize `i` and `j` to `0`, use `< n` instead of `<= n` in your loop conditions. — nouney, Dec 08 '15 at 13:21
Please do not edit code in questions so as to invalidate answers that already exist; it's very annoying to those contributors that spent time on answering:( — Martin James, Dec 08 '15 at 13:26
Sorry @MartinJames, my intentions were not to invalidate answers, but to provide complete code so contributors can review complete code which will help them to give proper answer. — Kiran Malvi, Dec 08 '15 at 13:32

score 2 · Answer 1 · edited May 23 '17 at 12:30

2

You are using variable n to create array without initializing it.You must always use a constant for initializing a static array

do something like this:

const int  n = SOME_VALUE;
int arr[n][n];
//rest remains same

also, you should use < n instead of <= n as pointed out by John.

if you want a dynamic array , then using STL vector will be better.

edited May 23 '17 at 12:30

Community

1
1

answered Dec 08 '15 at 13:19

mchouhan_google

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Even if it was initialized, he will get an error: `i<=n` should be `i – nouney Dec 08 '15 at 13:20
I've initialized it, The value is taken from user in other part of code. – Kiran Malvi Dec 08 '15 at 13:21
@KiranMalvi that may be, but 'int n, arr[n][n];' suggests otherwise. – Martin James Dec 08 '15 at 13:24
@MartinJames Ohh yeah got my error. Before even initializing value to var n i was putting n to arr[n][n]. Thanks – Kiran Malvi Dec 08 '15 at 13:28

score 0 · Answer 2 · answered Dec 08 '15 at 13:21

0

You are not initialising the n variable and also your loop should be

for (i=0; i<n; i++)

Array indices in C++ start from zero

Same for the j loop

answered Dec 08 '15 at 13:21

John Demetriou

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Obi-Wan errors? hmm, I know of yoda expressions http://www.devsanon.com/2015/11/usefulness-of-yoda-expressions-in.html but Obi-Wan errors? never heard of those – John Demetriou Dec 08 '15 at 13:23

SIGSEGV Error (Probably Array Index Out Of Bound)

2 Answers2