Example: Parallel Region in C

int x,y, z[1000];

#pragma omp threadprivate (x)

void fun(int a)

{

const int c = 1;

int i = 0;

#pragma omp parallel default(none)

private(a) shared(z)

{

int j = omp_get_thread_num();

a = z[j];

x = c;

z[i] = y;

#pragma omp for firstprivate(y)

for(int i=0;i᝺i++)z[i] = y;

z[i] = y;

} /* end pragma parallel */

printf(“%d\n”,a);

}

x will be made local to each thread

and will keep the value assigned by

each thread in a second parallel reg

Constant c will be propagated inside

the parallel region

j is defined as automatic local var

and assigned to the current #threads

a is defined in void fun(int a)

-> private(a), therefore fresh copy of

int “a” is created in each parallel thread

z[i] = y is illegal because

y and i are unknown:

there is no default scope

int y is global; firstprivate(y)

will create a fresh copy of int “y” and

initialize it to the global value;

i is a local private variable in block

a here is the original int a passed to fun.

There is no access to private variables outside parallel region

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