OpenMP and C99 data

Question

How does OpenMP handle data declared inside a parallel partition? Prior to C99, I would use the private () clause to specify local stream data, e.g.

int i, x;
#pragma omp parallel for private(x)
for (i=0; i<n; i++) {
   x=i;
}

Now that C99 allows you to mix data and code, I prefer to declare variables just before using them. Does a loop ad guarantee that it is threadable? For example, the following is valid:

#pragma omp parallel for
for (int i=0; i<n; i++) {
   int x=i;
}

I tried to add private (x) just in case, but my compiler objects (perhaps because x has not been declared yet).

Answer 1

, , , (, shared private). 2.9.1.1 OMP3.

OpenMP Standard 3.0, 2.9.1.1: (p78, 12) " , ". , OpenMP. , C99 x ; , , , x , . , , .

Answer 2

C x for. , .

i. C89 for.  OMP "" , .

int i;
#pragma omp parallel for
for (i=0; i<n; i++) {
   int x=i;
}

C99 .