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(g77-300.info)Language Extensions

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Language Extensions
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   `g77' offers several extensions to FORTRAN 77 language that `f2c'
doesn't:

   * Automatic arrays

   * `CYCLE' and `EXIT'

   * Construct names

   * `SELECT CASE'

   * `KIND=' and `LEN=' notation

   * Semicolon as statement separator

   * Constant expressions in `FORMAT' statements (such as
     `FORMAT(I<J>)', where `J' is a `PARAMETER' named constant)

   * `MvBits' intrinsic

   * `libU77' (Unix-compatibility) library, with routines known to
     compiler as intrinsics (so they work even when compiler options
     are used to change the interfaces used by Fortran routines)

   `g77' also implements iterative `DO' loops so that they work even in
the presence of certain "extreme" inputs, unlike `f2c'.  Note: Loops.

   However, `f2c' offers a few that `g77' doesn't, such as:

   * Intrinsics in `PARAMETER' statements

   * Array bounds expressions (such as `REAL M(N(2))')

   * `AUTOMATIC' statement

   It is expected that `g77' will offer some or all of these missing
features at some time in the future.