Although the presence in Fortran 90 of the module subprogram, the internal subprogram, and a greatly expanded collection of intrinsic procedures should reduce the heavy reliance on external procedures that has characterized Fortran in the past, the external subprogram can still be expected to continue to play an important role. But the interface between a routine and an external procedure that it invokes was too simple in traditional Fortran to accommodate many of the capabilities desired for Fortran 90. In order for the new features to be employed with external procedures, as well as with module and internal procedures, the Fortran 90 standard introduces a mechanism known as the “interface body.”
KeywordsMain Program Actual Argument Test Driver Module Procedure External Function
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