c - 在 #define 中使用 openmp pragma

Question

Possible Duplicates:
C/C++ pragma in define macro
Conditional “pragma omp”

如何在宏定义中使用 OpenMP 编译指示？例如

#define A() { \
 ...a lot of code... \
 #pragma omp for     \
 for(..)             \
  ..do_for..         \
 ...another a lot of code \
 }

Answer 1

正如这里的回答Conditional "pragma omp"

C99 has the _Pragma keyword that allows you to place what otherwise would be #pragma inside macros. Something like

  #define OMP_PARA_INTERNAL _Pragma("omp parallel for")

所以，

#define OMP_PARA_FOR _Pragma("omp for")
#define A() { \
 ...a lot of code... \
 OMP_PARA_FOR     \
 for(..)             \
  ..do_for..         \
 ...another a lot of code \
 }

多个_Pragma可以组合为一元运算符，例如:

_Pragma("first pragma") _Pragma("Second pragma")