The first int in one of two arrays is assigned 0 when I leave the for loop in which I assigned them values

I am chopping off every digit from a long "n" starting with the last and assigning them into two alternating arrays x[] & y[] using a for loop.

I was expecting the first int in the array x[0] to be a non 0 int & when i print inside the loop it gives expected results but if i print after the loop, just the first int of the second array x[0] is 0? everything else works as intended?

    int x[8];
    int y[8];
    long n = 4003600000000014;
    int d = 0; 
    printf("x before: ");
    for (long j = n; j > 0; j /= 10)
    {
        y[d] = n % 10;
        n /= 10;
        x[d] = n % 10;
        // debug to print x
        printf("%d, ", x[d]);
        n /= 10;
        d++;
    }
    //debug print
    printf("\n");
    printf("x after: ");
    for(int fu = 0; fu < 8; fu++)
    {
        printf("%d, ", x[fu]);
    }
    printf("\n");

the long "n" is just a test example it should be able to take any long

>Solution :

The problem is the for loop

for (long j = n; j > 0; j /= 10)
{
    y[d] = n % 10;
    n /= 10;
    x[d] = n % 10;
    // debug to print x
    printf("%d, ", x[d]);
    n /= 10;
    d++;
}

It has more iterations then the sizes of the arrays x and y.

In the for loop statement the variable j is divided by 10 only one time in each iteration of the loop

for (long j = n; j > 0; j /= 10)
                        ^^^^^^^

But within the body of the loop the variable n is divided by 10 two times

    y[d] = n % 10;
    n /= 10;
    ^^^^^^^^
    x[d] = n % 10;
    // debug to print x
    printf("%d, ", x[d]);
    n /= 10;
    ^^^^^^^
    d++;

As a result within the for loop there are accesses of memory beyond the arrays x and y.

You could rewrite your loop the following way

for (long j = n; j > 0; )
{
    y[d] = j % 10;
    j /= 10;
    x[d] = j % 10;
    // debug to print x
    printf("%d, ", x[d]);
    j /= 10;
    d++;
}