Example 1
A Multi-threaded “Hello World” Program
Example Code |
Sample Output |
#include “omp.h”
void main(){
#pragma omp parallel
{
int id = omp get thread num();
printf(“hello(%d)”,ID);
}
} |
hello(0) hello(3) hello(1)
hello(2)
hello(1) hello(2) hello(0)
hello(3) |
“IF” Clause
If an “if” clause is present it must evaluate to .TRUE. (Fortran) or non-zero (C/C++) in order to create a team of threads. Otherwise, the region is executed serially by master thread.
Example 2
A Multi-threaded “Hello World” Program With Clauses
#include “omp.h”
void main( ){
int x = 10;
#pragma omp parallel if(x > 10) num threads(4)
{
int id = omp get thread num();
printf(“hello(%d)”,ID);
}
}
- Num threads clause to request certain no of threads
- Omp get thread num() runtime function to return thread ID
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