How to properly use array subscripting notation?

Question

I am trying to read correctly this :

*(strarray[i]+j)=0;

I was understanding something like :

strarray[i][++j] = 0;

or

strarray[i][++j] = '\0';

but is not exactly the same. How could it be written correctly as an array subscripting notation?

++j and +j have nothing to do with each other. ++j CHANGES j itself while +j simply adds j's value to whatever comes before in the code. — Marc B
– Marc B, Commented Sep 14, 2016 at 21:07
yes, Nikita, it is char**. The answer posted below solved my confusion. — Mr'Black
– Mr'Black, Commented Sep 14, 2016 at 21:13

Sourav Ghosh · Accepted Answer · 2016-09-14 21:08:09Z

5

Using the postfix array subscripting notation,

*(strarray[i]+j)=0;

will be

 strarray[i][j]=0;

Quoting the C11 standard, chapter §6.5.2.1, Array subscripting

A postfix expression followed by an expression in square brackets [] is a subscripted designation of an element of an array object. The definition of the subscript operator [] is that E1[E2] is identical to (*((E1)+(E2))). [...]

In your case, you can consider E1 as strarray[i] and E2 as j.

answered Sep 14, 2016 at 21:08

Sourav Ghosh

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3 Comments

Mr'Black Over a year ago

Thanks Sourav, it works, that little + was disturbing. i will check more about Array subscripting.

blackpen Over a year ago

Nice reference to C11.

jforberg Over a year ago

Nice. And the general rule here is: when we say a[i] we always mean *(a + i).

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