Open MP - clauses

The table below summarizes which clauses are accepted by which OpenMP directives.

Clause	Description
copyin	Allows threads to access the master thread’s value, for a threadprivate variable.
copyprivate	Specifies that one or more variables should be shared among all threads.
default	Specifies the behavior of unscoped variables in a parallel region.
firstprivate	Specifies that each thread should have its own instance of a variable, and that the variable should be initialized with the value of the variable, because it exists before the parallel construct.
if	Specifies whether a loop should be executed in parallel or in serial.
lastprivate	Specifies that the enclosing context’s version of the variable is set equal to the private version of whichever thread executes the final iteration (for-loop construct) or last section (#pragma sections).
nowait	Overrides the barrier implicit in a directive.
num_threads	Sets the number of threads in a thread team.
ordered	Required on a parallel for-loop statement if an ordered directive is to be used in the loop.
private	Specifies that each thread should have its own instance of a variable.
reduction	Specifies that one or more variables that are private to each thread are the subject of a reduction operation at the end of the parallel region.
schedule	Applies to the for directive.
shared	Specifies that one or more variables should be shared among all threads.

Some examples next: