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发表于 2003-6-23 22:23:17
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大哥，请问如何在VC中调用Fortran程序？ (无内容)
Example 1: Main Program in C, with Subroutines in C, C++, and FORTRAN
The C program is nothing out of the ordinary: it defines two variables, and calls various functions that change those variables' values. C requires that we use a "call by reference" syntax to make these changes persistent, rather than its default "call by value" method. Note that the name of the FORTRAN function called from the C program is ffunction_, a name we extracted via the nm command shown above. Note also that the C++ function has an extern "C" directive above the code of the function, indicating not that cppfunction() is written in C, but that it is called from a C-style interface instead of a C++ interface.
File cprogram.c:
#include <stdio.h>
int main(void) {
float a=1.0, b=2.0;
printf("Before running Fortran function:\n");
printf("a=%f\n",a);
printf("b=%f\n",b);
ffunction_(&a,&b);
printf("After running Fortran function:\n");
printf("a=%f\n",a);
printf("b=%f\n",b);
printf("Before running C++ function:\n");
printf("a=%f\n",a);
printf("b=%f\n",b);
cppfunction(&a,&b);
printf("After running C++ function:\n");
printf("a=%f\n",a);
printf("b=%f\n",b);
printf("Before running C function:\n");
printf("a=%f\n",a);
printf("b=%f\n",b);
cfunction(&a,&b);
printf("After running C function:\n");
printf("a=%f\n",a);
printf("b=%f\n",b);
return 0;
}
File ffunction.f:
subroutine ffunction(a,b)
a=3.0
b=4.0
end
File cppfunction.C:
extern "C" {
void cppfunction(float *a, float *b);
}
void cppfunction(float *a, float *b) {
*a=5.0;
*b=6.0;
}
File cfunction1.c:
void cfunction(float *a, float *b) {
*a=7.0;
*b=8.0;
}
Compilation Steps: each program is compiled into an object file using the appropriate compiler with the -c flag. After all the object files are created, the final gcc command links the object files together into a single executable:
mwr@ch208m:~$ gcc -c cprogram.c
mwr@ch208m:~$ g77 -c ffunction.f
mwr@ch208m:~$ g++ -c cppfunction.C
mwr@ch208m:~$ gcc -c cfunction1.c
mwr@ch208m:~$ gcc -o cprogram cprogram.o ffunction.o cppfunction.o cfunction1.o
mwr@ch208m:~$
Though this example problem does not require it, many of the math functions (for example, sin, cos, pow, etc.) require that you also link in the libm math library. Add a -lm flag to the final gcc command above to link in the math library.
Results:
mwr@ch208m:~$ ./cprogram
Before running Fortran function:
a=1.000000
b=2.000000
After running Fortran function:
a=3.000000
b=4.000000
Before running C++ function:
a=3.000000
b=4.000000
After running C++ function:
a=5.000000
b=6.000000
Before running C function:
a=5.000000
b=6.000000
After running C function:
a=7.000000
b=8.000000
mwr@ch208m:~$
Example 2: Main Program in C++, with Subroutines in C, C++, and FORTRAN
The only differences between the C++ code in a normal program is that we have to account for the C and FORTRAN subroutines expecting to be called with a C-style interface, and also that the FORTRAN compiler will append an underscore to the FORTRAN function name. Also, since the C++ function is held in a separate file from the C++ main program, we need to declare a function prototype before the main program code.
File cppprogram.C:
#include <iostream.h>
extern "C" {
void ffunction_(float *a, float *b);
}
extern "C" {
void cfunction(float *a, float *b);
}
void cppfunction(float *a, float *b);
int main() {
float a=1.0, b=2.0;
cout << "Before running Fortran function:" << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
ffunction_(&a,&b);
cout << "After running Fortran function:" << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
cout << "Before running C function:" << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
cfunction(&a,&b);
cout << "After running C function:" << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
cout << "Before running C++ function:" << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
cppfunction(&a,&b);
cout << "After running C++ function:" << endl;
cout << "a=" << a << endl;
cout << "b=" << b << endl;
return 0;
}
File cfunction1.c:
void cfunction(float *a, float *b) {
*a=7.0;
*b=8.0;
}
File ffunction.f:
subroutine ffunction(a,b)
a=3.0
b=4.0
end
Compilation Steps:
mwr@ch208m:~$ g++ -c cppprogram.C
mwr@ch208m:~$ gcc -c cfunction1.c
mwr@ch208m:~$ g++ -c cppfunction1.C
mwr@ch208m:~$ g77 -c ffunction.f
mwr@ch208m:~$ g++ -o cppprogram cppprogram.o cfunction1.o cppfunction1.o ffunction.o
mwr@ch208m:~$
Results:
mwr@ch208m:~$ ./cppprogram
Before running Fortran function:
a=1
b=2
After running Fortran function:
a=3
b=4
Before running C function:
a=3
b=4
After running C function:
a=7
b=8
Before running C++ function:
a=7
b=8
After running C++ function:
a=5
b=6
mwr@ch208m:~$
Example 3: Main Program in FORTRAN, with Subroutines in C, C++, and Fortran
Though the non-FORTRAN subroutines don't have any underscores after their names in the main FORTRAN program, running the nm command on fprogram.o shows that the FORTRAN program expects that they'll have underscores appended to the function name internally. Therefore, in both the C and C++ files, we need to write the function prototype statement accordingly, with an underscore after the function name. We also must use the extern "C" directive in the C++ file, indicating that the C++ function is called with a C-style interface, similar to the first example.
File fprogram.f:
program fprogram
real a,b
a=1.0
b=2.0
print*,'Before Fortran function is called:'
print*,'a=',a
print*,'b=',b
call ffunction(a,b)
print*,'After Fortran function is called:'
print*,'a=',a
print*,'b=',b
print*,'Before C function is called:'
print*,'a=',a
print*,'b=',b
call cfunction(a,b)
print*,'After C function is called:'
print*,'a=',a
print*,'b=',b
print*,'Before C++ function is called:'
print*,'a=',a
print*,'b=',b
call cppfunction(a,b)
print*,'After C++ function is called:'
print*,'a=',a
print*,'b=',b
stop
end
File ffunction.f:
subroutine ffunction(a,b)
a=3.0
b=4.0
end
File cppfunction2.C:
extern "C" {
void cppfunction_(float *a, float *b);
}
void cppfunction_(float *a, float *b) {
*a=5.0;
*b=6.0;
}
File cfunction2.c:
void cfunction_(float *a, float *b) {
*a=7.0;
*b=8.0;
}
Compilation Steps:
mwr@ch208m:~$ g77 -c fprogram.f
mwr@ch208m:~$ g77 -c ffunction.f
mwr@ch208m:~$ g++ -c cppfunction2.C
mwr@ch208m:~$ gcc -c cfunction2.c
mwr@ch208m:~$ g77 -lc -o fprogram fprogram.o ffunction.o cppfunction2.o cfunction2.o
mwr@ch208m:~$
Results:
mwr@ch208m:~$ ./fprogram
Before Fortran function is called:
a= 1.
b= 2.
After Fortran function is called:
a= 3.
b= 4.
Before C function is called:
a= 3.
b= 4.
After C function is called:
a= 7.
b= 8.
Before C++ function is called:
a= 7.
b= 8.
After C++ function is called:
a= 5.
b= 6.
mwr@ch208m:~$
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