How to access a element at array[-1] position ?

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C++

int a[10];
    int i;
    for (i=0; i<10; i++)
      a[i] = i;
    printf("%d", a[-1]);
    return 0;

Posted 11-Feb-13 3:34am

mvigsnhwar

Updated 11-Feb-13 3:42am

Maciej Los

v2

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3 solutions

Solution 3

Yes, you can access to an array element [i-1] only if the index of position is bigger then 0 (in zero-based arrays).

C++

int i = 0;
int j = 0;
for (i=0; i<10; i++)
{
    printf("%d", a[i]);
    if (i>0)
    {
    j=i-1;
    printf("%d", a[j]);
    }
}

Posted 11-Feb-13 3:51am

Maciej Los

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Matthew Faithfull · Accepted Answer · 2013-02-11T03:42:00

Solution 1

0. You are already accessing the array at -1 position which is outside the array.
1. Don't do this.
2. Whatever the reason for wanting to do this there is a better way to do it.
3. See number 1.
...
...
-1. BANG! your program is dead.

Posted 11-Feb-13 3:42am

Matthew Faithfull

Comments

Maciej Los 11-Feb-13 9:43am

Short and to the point! +5!

Albert Holguin 11-Feb-13 11:24am

Pretty much... +5

Mehdi Gholam · Accepted Answer · 2013-02-11T03:48:00

Solution 2

You can't, if you mean the last but one element then you have to do a[(sizeof(a) / sizeof(a[0])-1].

Posted 11-Feb-13 3:48am

Mehdi Gholam