5.3 Linking With Legacy FORTRAN 77-Compiled Routines

• To mix f77 and f95 object binaries, link with f95 compiler and the -xlang=f77 option. Perform the link step with f95 even if the main program is an f77 program

• Example: Compiling an f95 main program with an f77 object file.

  demo% cat m.f95
  CHARACTER*74 :: c = ’This is a test.’
     CALL echo1( c )
  END
  demo% f95 -xlang=f77 m.f95 sub77.o
  demo% a.out
   This is a test.
  demo%

• The FORTRAN 77 library and intrinsics are available to f95 programs and are listed in the Fortran Library Reference Manual.

  Example: f95 main calls a routine from the FORTRAN 77 library.

  demo% cat tdtime.f95
          REAL e, dtime, t(2)
          e = dtime( t )
          DO i = 1, 100000
             as = as + cos(sqrt(float(i)))
          END DO
          e = dtime( t )
          PRINT *, ’elapsed:’, e, ’, user:’, t(1), ’, sys:’, t(2)
          END
  demo% f95 tdtime.f95
  demo% a.out
  elapsed: 0.14 , user: 0.14 , sys: 0.0E+0
  demo%

  See dtime(3F).