Manual Reference Pages - program (7fortran)

NAME

PROGRAM(3) - [PROGRAM UNITS] Absolute value

SYNOPSIS

Basic Fortran program sections:
        [ PROGRAM [program-name]]

            [ specification-part ]
            [ execution-part ]
            [ internal-subprogram-part ]

        end [PROGRAM [program-name]]
A PROGRAM directive optionally marks the beginning of a main program.
A main program is the starting point for execution of a program.
The main program may be defined by means other than Fortran; in that case, the program shall not contain a Fortran main-program program unit at all.
The optional name of the main program has no explicit use within the Fortran language. It is available for documentation and for possible use by a processor.
A processor might implement an unnamed program unit by assigning it a global identifier that is not used elsewhere in the program. This could be done by using a default name that does not satisfy the rules for Fortran names, but if the name is specified it must conform to the rules for a Fortran identifier (composed from the ASCII alphanumeric characters and underscore, up to 63 characters, must begin with a letter).
The PROGRAM statement is optional but is almost always present in modern programs. Since it is optional a Fortran main program block is defined as a program unit that does not contain a SUBROUTINE, FUNCTION, MODULE, SUBMODULE,or BLOCKDATA statement as its first statement.
Note that the PROGRAM block is not required to be the first program unit in a file. Modules or procedure definitions or other program units may proceed it and most may follow it (A module must be defined before a reference to it is made).
The program-name shall not be included in the end-program-stmt unless the optional program-stmt is used. If included, it shall be identical to the program-name specified in the program-stmt.
NOTE1 The program name is global to the program.
An example of a main program is:

PROGRAM ANALYZE

REAL A, B, C (10,10)
! Specification part

CALL FIND
! Execution part

CONTAINS

SUBROUTINE FIND
! Internal subprogram [char46] . .

END SUBROUTINE FIND

END PROGRAM ANALYZE

A reference to a Fortran main-program shall not appear in any program unit in the program, including itself. That is, you cannot call or jump to a main program from another program unit such as a module or procedure.

GLOSSARY

program
set of Fortran program units and entities defined by means other than Fortran that includes exactly one main program.
program unit
A main program, external subprogram, module, submodule, or block data program unit.

Nemo Release 3.1

program (7fortran)

November 02, 2024

Generated by manServer 1.08 from 85ae8e24-9736-4b11-bc5a-08c97c27d5ce using man macros.

REAL A, B, C (10,10)
	! Specification part
CALL FIND
	! Execution part