FORTRAN, Statements, STRUCTURE
*Conan The Librarian (sorry for the slow response - running on an old VAX)
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VMS Help FORTRAN, Statements, STRUCTURE *Conan The Librarian (sorry for the slow response - running on an old VAX) |
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Indicates the beginning of the record structure declaration and
defines the name of the structure. Declaration format:
STRUCTURE [/str/][fnlist]
fdcl
[fdcl]
...
[fdcl]
END STRUCTURE
str Identifies a structure name, which is used in
following RECORD statements to refer to the
structure. A structure name is enclosed in slashes.
fnlist Identifies field names when used in a substructure
declaration.(Only allowed in nested structure
declarations.)
fdcl (Also called the declaration body.) Is any
declaration or combination of declarations of
substructures, unions, or typed data, or
PARAMETER statements.
Following RECORD statements use the structure name to refer to the
structure. A structure name must be unique among structure names,
but structures can share names with variables (scalar or array),
record fields, PARAMETER constants, and common blocks.
Structure declarations can be nested (contain one or more other
structure declarations). A structure name is required for the
structured declaration at the outermost level of nesting, and
optional for the other declarations nested in it. However, if you
wish to reference a nested structure in a RECORD statement in your
program, it must have a name.
Structure, field, and record names are all local to the defining
program unit. When records are passed as arguments, the fields
must match in type, order, and dimension.
Unlike type declaration statements, structure declarations do not
create variables. Structured variables (records) are created when
you use a RECORD statement containing the name of a previously
declared structure. The RECORD statement can be considered as a
kind of type statement. The difference is that aggregate items,
not single items, are being defined.
Within a structure declaration, the ordering of both the statements
and the field names within the statements is important because this
ordering determines the order of the fields in records.
In a structure declaration, each field offset is the sum of the
lengths of the previous fields. The length of the structure,
therefore, is the sum of the lengths of its fields. The structure
is packed; you must explicitly provide any alignment that is needed
by including, for example, unnamed fields of the appropriate
length.
In the following example, the declaration defines a structure named
DATE. This structure contains three scalar fields: DAY
(LOGICAL*1), MONTH (LOGICAL*1), and YEAR (INTEGER*2).
STRUCTURE /DATE/
LOGICAL*1 DAY, MONTH
INTEGER*2 YEAR
END STRUCTURE
Additional Information (explode) :
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