# #define SEQAN_OMP_PRAGMA
Portable conditional `#pragma` issuing if OpenMP is enabled.

Defined in | <seqan/parallel.h>
Signature | `SEQAN_OMP_PRAGMA(x)`

## Parameters

`x` | The string to issue behind `#pragma omp`.

## Detailed Description

### Remarks

This macro uses portable pragma generation, dependent on the macro `_OPENMP` being defined (as by the OpenMP standard).

This is useful for disabling OpenMP pragmas on compilers that do not support OpenMP or when OpenMP is not enabled to suppress warnings.

### Example

Parallelize loop with OpenMP if OpenMP is enabled:

    SEQAN_OMP_PRAGMA(parallel for)  // becomes: #pragma omp parallel for
    for (int i = 0; i < x; ++i)
    {
        // Do work.
    }

Make an addition atomic if OpenMP is enabled:

    SEQAN_OMP_PRAGMA(parallel atomic)  // becomes: #pragma omp parallel atomic
    i += 1;

## Data Races

If not stated otherwise, concurrent invocation is not guaranteed to be thread-safe.

#### Dox Sources

    /*!
     * @macro SEQAN_OMP_PRAGMA
     *
     * @headerfile <seqan/parallel.h>
     *
     * @brief Portable conditional <tt>#pragma</tt> issuing if OpenMP is enabled.
     *
     * @signature SEQAN_OMP_PRAGMA(x)
     *
     * @param x The string to issue behind <tt>#pragma omp</tt>.
     *
     * @section Remarks
     *
     * This macro uses portable pragma generation, dependent on the macro
     * <tt>_OPENMP</tt> being defined (as by the OpenMP standard).
     *
     * This is useful for disabling OpenMP pragmas on compilers that do not support
     * OpenMP or when OpenMP is not enabled to suppress warnings.
     *
     * @section Example
     *
     * Parallelize loop with OpenMP if OpenMP is enabled:
     *
     * @code{.cpp}
     * SEQAN_OMP_PRAGMA(parallel for)  // becomes: #pragma omp parallel for
     * for (int i = 0; i < x; ++i)
     * {
     *     // Do work.
     * }
     * @endcode
     *
     *
     * Make an addition atomic if OpenMP is enabled:
     *
     * @code{.cpp}
     * SEQAN_OMP_PRAGMA(parallel atomic)  // becomes: #pragma omp parallel atomic
     * i += 1;
     * @endcode
     */