How to pass a array of string from fortran to c?

Question

I want to pass a array of string which I filled in fortran code to C. However, every times I tried to check the result I found that each one of the character string is printed as a whole array in C. Can anyone help through this? This is fortran part of code:

        SUBROUTINE hello (Characters)
CHARACTER*(16)  Characters(5)
Characters=(/"ABCD","BCDF","CVFG","D HG","J67F"/)
return
END

and this is C code:

    void hello_(char *[16]);
    int main(int argc,char **args)
    {
    char        Character2[5][16];
    int         j;
    hello_(&Character2);
    for(j=0;j<5;j++){
    printf("String [ %d ] = %s \n",j,Character2[j]);
    }
    return 0;
    }

The results I get is this:

 String [ 0 ] = ABCD            BCDF            CVFG            D HG                  J67F            `����U 
 String [ 1 ] = BCDF            CVFG            D HG            J67F            `����U 
 String [ 2 ] = CVFG            D HG            J67F            `����U 
 String [ 3 ] = D HG            J67F            `����U 
 String [ 4 ] = J67F            `����U  

I want to know why I can't access to each one of those strings which I passed from fortran to C? I mean, how can I make sure that ,like, Character2[1] is exactly what I made in fortran, "ABCD"! Thanks

Answer 1

Since the FORTRAN strings are not NUL terminated, the C code will not be able to detect the end of the string being printed.

Since your strings are meant to be no longer than a certain length, you can specify that in your print statement (although, it is unclear to me that FORTRAN will fill with spaces if you don't provide a long enough string):

printf("String [ %d ] = %.4s \n",j,Character2[j]);

If your FORTRAN code knows it will be called from C, then it should add the NUL byte to the strings before returning the array back to the caller.