C和Fortran互相传递动态数组
C和Fortran的相互调用传递数值的方法有很多，但是F03标准的出笼，使用ISO_C_BINDING进行C和Fortran的互相调用有着更显著的优势：
1、与编译器和平台无关；
2、Fortran中可以定义C的数据类型；
3、使用Interface接口声明，清晰明了；
这里主要介绍C传递动态数组给Fortran的一种解决思路。
C代码：
1 #include <stdlib.h> /* malloc */ 2 #include <stdio.h> /* printf */ 3 struct my_struct{ 4 int num; /* length of array*/ 5 int *array; /* dynamic array*/ 6 }my_struct; 7 int j=12; 8 struct my_struct make_array(){ 9 struct my_struct tmp; 10 int i; 11 tmp.num = j; 12 /* initialize array */ 13 tmp.array = (int*)malloc(tmp.num*sizeof(int)); 14 for(i=0;i<tmp.num;i++)tmp.array[i]=(i+1)*(i+1); 15 j+=3; 16 return tmp; 17 }
Fortran代码：
program f_call_c use,intrinsic::iso_c_binding implicit none ! define same struct in C type,bind(c)::my_struct integer(c_int)::nn type(c_ptr)::array end type interface type(my_struct) function make_array() bind(c,name='make_array') import !! Make iso_c_binding and my_struct visible here end function endinterface integer(C_INT), pointer :: array(:) => NULL() type(my_struct)::xyz integer::j do j=1,3 xyz = make_array() call c_f_pointer(xyz%array,array,[xyz%nn]) write(*,*)xyz%nn write(*,*)array enddo end program
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2014-03-14 更新 C传递动态数组到Fortran的代码
2014-03-17 补充Fortran传递动态数组到C的代码
1、根据gfortran的使用手册：If a pointer is a dummy-argument of an interoperable procedure, it usually has to be declared using the VALUE attribute. void* matches TYPE(C_PTR), VALUE, while TYPE(C_PTR) alone matches void**.
2、增加的代码在C中定义全局指针用于分配内存开辟动态数组，然后Fortran调用，最后C代码中释放内存
3、gfortran可以直接同时编译c和fortran文件，gcc同样亦可不过需要添加编译参数
小结：推荐使用Function而不是subroutine定义C的interface，分配给动态数组的内存要清空，避免内存泄漏，使用指针的话用完后记得指向空指针。
************************************
C传递动态数组到Fortran
C pass dynamic array to Fortran
************************************
C代码：
#include <stdlib.h>
#include <stdio.h>
// define a struct
- struct conn{
int ind;
float *list;
int length;
};
// define a pointer struct
struct conn *abc=NULL;
// length of dynamic array
int array_len=0,struct_len=0;
// define a pointer to pointer
float *vector2=NULL;
/* float array printing function */
void print_float_array(float *array, int len)
- {
int i;
for(i=0; i<len; i++)
printf("%f | ", array[i]);
putchar('\n');
}
void clear_array(void)
- {
- if(vector2!=NULL){
free(vector2);
vector2=NULL;
printf("Clear pointer successfully\n");
}
- else{
printf("Already NULL!\n");
}
}
// Method 1
void dynamic_array(int n1,float **a,int *n2)
- {
int i;
if(vector2!=NULL)clear_array();
// Allocate array
vector2 = (float*)malloc(n1*2*sizeof(float));
// Set values
for(i=0;i<n1*2;i++){vector2[i] = (float)i*i+1.0;}
// display array
print_float_array(vector2,n1*2);
//
*a = vector2;
*n2 = 2*n1;
// Set length of array
array_len = n1*2;
}
// Method 2
float* d_array(int n1,int *n2)
- {
int i;
if(vector2!=NULL)clear_array();
// Allocate array
vector2 = (float*)malloc(n1*2*sizeof(float));
// Set values
for(i=0;i<n1*2;i++){vector2[i] = (float)i*i+1.0;}
print_float_array(vector2,n1*2);
*n2 = 2*n1;
array_len = n1*2;
return vector2;
}
void clear_struct(void)
- {
int i;
- if(abc!=NULL){
- for(i=0;i<struct_len;i++){
free(abc[i].list);
abc[i].list=NULL;
}
struct_len = 0;
free(abc);
abc = NULL;
printf("Clear struct array successfully!");
putchar('\n');
}
- else{
printf("Already NULL\n");
}
}
// Pass dynamic struct array
struct conn *d_struct(int n1,int *n2)
- {
int i,j;
if(abc!=NULL)clear_struct();
// Allocate sturct array
abc = (struct conn*)malloc((n1+1)*sizeof(struct conn));
// Set values
- for(i=0;i<n1+1;i++){
abc[i].list = (float*)malloc((i+2)*sizeof(float));
abc[i].ind = i+1;
abc[i].length = i+2;
- for(j=0;j<i+2;j++){
abc[i].list[j] = (float)j*j+0.5;
}
}
*n2 = n1 + 1;
struct_len = n1 + 1;
return abc;
}
Fortran代码：
- module dynamic
use,intrinsic::iso_c_binding
implicit none
! Define struct
- type,bind(c)::connect
integer(c_int)::ind
type(c_ptr)::list
integer(c_int)::length
end type
- interface
! Method 1 via subroutine
- subroutine dynamic_array(length,a,n)bind(c,name='dynamic_array')
import
implicit none
integer(c_int),intent(in),value::length
integer(c_int),intent(out)::n
type(c_ptr),intent(out)::a
end subroutine
! Mehtod 2 via function
- type(c_ptr) function dynamic_array2(length,n)bind(c,name='d_array')
import
implicit none
integer(c_int),intent(in),value::length
integer(c_int),intent(out)::n
end function
! Pass dynamic struct array via function
- type(c_ptr) function dynamic_struct(length,n)bind(c,name='d_struct')
import
implicit none
integer(c_int),intent(in),value::length
integer(c_int),intent(out)::n
end function
! Clear struct array
- subroutine clear_struct()bind(c,name='clear_struct')
import
implicit none
end subroutine
! Clear array
- subroutine clear_array()bind(c,name='clear_array')
import
implicit none
end subroutine
end interface
end module
- program test
use dynamic
implicit none
real,pointer::array(:)
integer,pointer::nn
type(c_ptr)::c_array,c_struct
type(connect),pointer::conn(:)
integer::i,j,k
nullify(array)
nn=>NULL()
c_array=c_null_ptr
i = 10
j = 0
call dynamic_array(i,c_array,j)
!c_array = dynamic_array2(i,j)
write(*,*)i,j
call c_f_pointer(c_array,array,[j])
write(*,*)
write(*,*)array
c_array=c_null_ptr
c_struct = c_null_ptr
array=>null()
i = 2*2
j = 0
c_struct = dynamic_struct(i,j)
write(*,*)i,j
call c_f_pointer(c_struct,conn,[j])
- do i=1,j
array=>null()
call c_f_pointer(conn(i)%list,array,[conn(i)%length])
write(*,*)"Index:",i
write(*,*)"List:",(array(k),k=1,size(array))
enddo
call clear_struct()
call clear_array()
end program
************************************
Fortran传递动态数组到C
Fortran pass dynamic array to C
***********************************
Fortran代码：
- module f2c_dynamic
use,intrinsic::iso_c_binding
implicit none
integer(c_int),allocatable,target::ind(:)
contains
- type(c_ptr) function init_array(n1,n2)bind(c,name="allocArray")
implicit none
integer(c_int),intent(in),value::n1
integer(c_int),intent(out)::n2
integer::i
write(*,*)"************************"
write(*,*)"Fortran"
write(*,*)"************************"
write(*,*)"input:",n1,n2
call clear_array()
init_array = c_null_ptr
allocate(ind(n1+6))
- do i=1,n1+6
ind(i) = i**2+2
write(*,*)"index:",i," value:",ind(i)
enddo
n2 = n1 + 6
write(*,*)"array size:",n2
init_array = c_loc(ind(1))
write(*,*)"Return pointer"
return
end function
- subroutine init_array2(n1,n2,a)bind(c,name="allocArray2")
implicit none
integer(c_int),intent(in),value::n1
integer(c_int),intent(out)::n2
type(c_ptr),intent(out)::a
integer::i
write(*,*)"************************"
write(*,*)"Fortran"
write(*,*)"************************"
write(*,*)"input:",n1,n2
call clear_array()
a = c_null_ptr
allocate(ind(n1+2))
- do i=1,n1+2
ind(i) = i**3-1
write(*,*)"index:",i," value:",ind(i)
enddo
n2 = n1 + 2
write(*,*)"array size:",n2
a = c_loc(ind(1))
write(*,*)"Return pointer"
return
end subroutine
- subroutine clear_array()bind(c,name="clearArray")
implicit none
if(allocated(ind))then
deallocate(ind)
write(*,*)"Clear successfully"
endif
end subroutine
end module f2c_dynamic
C代码：
#include <stdlib.h> /* malloc */
#include <stdio.h> /* printf */
int *allocArray(int ,int *);// via fortran function
void allocArray2(int,int *,int **);// via fortran subroutine
void clearArray();
/* float array printing function */
void print_int_array(int *array, int len)
- {
int i;
for(i=0; i<len; i++)
printf("%d | ", array[i]);
putchar('\n');
}
int main(int argc,char *argv[])
- {
int n1=5;
int n2=0;
int *a=NULL;
int *b=NULL;
a=allocArray(n1,&n2);
printf("********************\nC output\ninput:%d size:%d\n",n1,n2);
print_int_array(a,n2);
clearArray();
n2 = 0;
n1 = 6;
allocArray2(n1,&n2,&b);
printf("********************\nC output\ninput:%d size:%d\n",n1,n2);
print_int_array(b,n2);
clearArray();
a=NULL;
b=NULL;
return 0;
}
