test

Fortran Programming Guide

Alternate Returns

Fortran's alternate returns mechanism is obsolescent and should not be used if portability is an issue. There is no equivalent in C to alternate returns, so the only concern would be for a C routine calling a Fortran routine with alternate returns.

The Sun Fortran implementation returns the int value of the expression on the RETURN statement. This is implementation dependent and its use should be avoided.

Table 11-17 Alternate Returns

C calls Fortran 

Running the Example 

int altret_ ( int * );

main ()

{

int k, m ;

k =0;

m = altret_( &k ) ;

printf( "%d %d\n", k, m);

}

------------------------------

SUBROUTINE ALTRET( I, *, *)

INTEGER I

I = I + 1

IF(I .EQ. 0) RETURN 1

IF(I .GT. 0) RETURN 2

RETURN

END

demo% cc -c tst.c

demo% f77 -o alt alt.f tst.o

alt.f:

altret:

demo% alt

1 2

The C routine receives the return value 2 from

the Fortran routine because it executed the

RETURN 2 statement.