# par-loops, Qpar-loops

Lets you select between old or new implementations of parallel loop support.

## Syntax

Linux and macOS: | -par-loops=keyword

Windows: | /Qpar-loops:keyword

## Arguments

keyword | Specifies which implementation to use. Possible values are:
new | Enables the new implementation of parallel-loop support. As a result, parallel C++ range-based loops and collapsing complex loop stacks will not result in compilation errors. This is the default.
old | Enables the old implementation of parallel-loop support. This is the same implementation that was supported in 18.0 and earlier releases.
default | This is the same as specifying new.

## Default

-par-loops=new or /Qpar-loops:new | The compiler uses the new implementation of parallel-loop support. Note that this setting may not yet be as stable as setting "old" since the implementation is new.

## Description

This option lets you select between old or new implementations of parallel loop support.

The new implementation handles parallel C++ range-based loops, and also collapsing of OpenMP* parallel loops with complicated bounds expressions, for which the previous implementation reported errors.

If your code has a parallel loop that is not handled by the previous implementation, we recommend that you enable use of the new implementation.

## IDE Equivalent

None

## Alternate Options

None

Parent topic: OpenMP* Options and Parallel Processing Options