OpenMP-Examples/sources/Example_taskloop_reduction.2.c

/*
* @@name:       taskloop_reduction.2.c
* @@type:       C
* @@compilable: yes, omp_5.0
* @@linkable:   yes
* @@expect:     success
*/
#include <stdio.h>

int array_sum(int n, int *v) {
    int i;
    int res = 0;

    #pragma omp taskgroup task_reduction(+: res)
    {
        if (n > 0) {
            #pragma omp task in_reduction(+: res)
            res = res + v[0];

            #pragma omp taskloop in_reduction(+: res) nogroup
            for(i = 1; i < n; ++i)
                res += v[i];
        }
    }

    return res;
}

int main(int argc, char *argv[]) {
    int n = 10;
    int v[10] = {1,2,3,4,5,6,7,8,9,10};

    #pragma omp parallel
    #pragma omp single
    {
        int res = array_sum(n, v);
        printf("The result is %d\n", res);
    }
    return 0;
}