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HP OpenVMS Systems Documentation |
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HP Fortran for OpenVMS
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RECORDSIZE is a nonstandard synonym for RECL (see Section 12.6.25).
The RECORDTYPE specifier indicates the type of records in a file. It takes the following form:
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typ
Is a scalar default character expression that evaluates to one of the following values:
' FIXED ' Indicates fixed-length records. ' VARIABLE ' Indicates variable-length records. ' SEGMENTED ' Indicates segmented records. ' STREAM ' Indicates stream-type variable length records. ' STREAM_CR ' Indicates stream-type variable length records, terminated with a carriage-return. ' STREAM_LF ' Indicates stream-type variable length records, terminated with a line feed.
When you open a file, default record types are as follows:
| ' FIXED ' | For relative or indexed files |
| ' FIXED ' | For direct access sequential files |
| ' VARIABLE ' | For formatted sequential access files |
| ' SEGMENTED ' | For unformatted sequential access files |
A segmented record is a logical record consisting of one or more variable-length records (segments). The logical record can span several physical records. Only unformatted sequential-access files with sequential organization can have segmented records; ' SEGMENTED ' must not be specified for any other file type.
Files containing segmented records can be accessed only by unformatted sequential data transfer statements.
Normally, if you do not use the RECORDTYPE specifier when you are accessing an existing file, the record type of the file is used. However, if the file is an unformatted sequential-access file with sequential organization and variable-length records, the default record type is ' SEGMENTED ' .
If you use the RECORDTYPE specifier when you are accessing an existing file, the type that you specify must match the type of the existing file.
If an output statement does not specify a full record for a file containing fixed-length records, the following occurs:
On record types and file organization, see the HP Fortran for OpenVMS User Manual.
The SHARED specifier indicates that the file is connected for shared
access by more than one program executing simultaneously. It takes the
following form:
12.6.28 SHARED Specifier
On file sharing, see the HP Fortran for OpenVMS User Manual.
12.6.29 STATUS Specifier
The STATUS specifier indicates the status of a file when it is opened. It takes the following form:
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sta
Is a scalar default character expression that evaluates to one of the following values:
' OLD ' Indicates an existing file. ' NEW ' Indicates a new file; if the file already exists, an error occurs. Once the file is created, its status changes to ' OLD ' . ' SCRATCH ' Indicates a new file that is unnamed (called a scratch file). When the file is closed or the program terminates, the scratch file is deleted. ' REPLACE ' Indicates the file replaces another. If the file to be replaced exists, it is deleted and a new file is created with the same name. If the file to be replaced does not exist, a new file is created and its status changes to ' OLD ' . ' UNKNOWN ' Indicates the file may or may not exist. If the file does not exist, a new file is created (using the next highest available version number) and its status changes to ' OLD ' .
The default is ' UNKNOWN ' . However, if you implicitly open a file using WRITE or you specify compiler option /NOF77 (or OPTIONS /NOF77), the default value is ' NEW ' . If you implicitly open a file using READ, the default value is ' OLD ' .
Scratch files (STATUS= ' SCRATCH ' ) are created on your default disk (SYS$DISK) and are not placed in a directory or given a name that is externally visible. To indicate a different device, use the FILE specifier.
The STATUS specifier can also appear in CLOSE statements to indicate the file's status after it is closed. However, in CLOSE statements the STATUS values are the same as those listed for the DISPOSE specifier (see Section 12.6.12). |
TYPE is a nonstandard synonym for STATUS (see Section 12.6.29).
The USEROPEN specifier indicates a user-written external function that controls the opening of the file. It takes the following form:
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function-name
Is the name of the user-written function to receive control.The function must be declared in a previous EXTERNAL statement; if it is typed, it must be of type INTEGER(4) (INTEGER*4).
The USEROPEN specifier lets experienced users use additional features of the operating system that are not normally available in Fortran.
On user-supplied functions to use with USEROPEN, including examples,
see the HP Fortran for OpenVMS User Manual.
12.7 REWIND Statement
The REWIND statement positions a sequential or direct access file at the beginning of the file (the initial point). It takes one of the following forms:
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io-unit
Is an external unit specifier.label
Is the label of the branch target statement that receives control if an error occurs.i-var
Is a scalar integer variable that is defined as a positive integer if an error occurs and zero if no error occurs.
The unit number must refer to a file on disk or magnetic tape, and the
file must be open for sequential,
direct, or append
access.
If a REWIND is done on a direct access file, the NEXTREC specifier is
assigned a value of 1.
A REWIND statement must not be specified for a file that is open for or keyed access.
If a file is already positioned at the initial point, a REWIND statement has no effect.
If a REWIND statement is specified for a unit that is not open, it has no effect.
The following statement repositions the file connected to I/O unit 3 to the beginning of the file:
REWIND 3 |
Consider the following statement:
REWIND (UNIT=9, IOSTAT=IOS, ERR=10) |
This statement positions the file connected to unit 9 at the beginning of the file. If an error occurs, control is transferred to the statement labeled 10, and a positive integer is stored in variable IOS.
The UNLOCK statement frees a record in an indexed, relative, or sequential file that was locked by a previous READ statement.
The UNLOCK statement takes one of the following forms:
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io-unit
Is an external unit specifier.label
Is the label of the branch target statement that receives control if an error occurs.i-var
Is a scalar integer variable that is defined as a positive integer if an error occurs and zero if no error occurs.
If no record is locked, the UNLOCK statement has no effect.
The following statement frees any record previously read and locked in the file connected to I/O unit 4:
UNLOCK 4 |
Consider the following statement:
UNLOCK (UNIT=9, IOSTAT=IOS, ERR=10) |
This statement frees any record previously read and locked in the file connected to unit 9. If an error occurs, control is transferred to the statement labeled 10, and a positive integer is stored in variable IOS.
In addition to specifying options on the compiler command line, you can specify the following statements in a program unit to influence compilation:
The DICTIONARY statement incorporates common data dictionary (CDD) data definitions into the current HP Fortran source program during compilation. The statement can occur any place in a Fortran source program where a STRUCTURE statement can occur.
The DICTIONARY statement takes the following form:
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cdd-path
Is interpreted as the full or relative pathname of a CDD object./[NO]LIST
Controls whether the source code representation of the resulting structure declaration is listed in a compilation source listing. The default is /NOLIST. /LIST and /NOLIST must be spelled completely.
There are two types of CDD pathnames: full and relative. Their form must conform to the rules for forming CDD pathnames.
A full CDD pathname begins with CDD$TOP and specifies the given names of all its descendants; it is a complete path to the record definition. Multiple descendant names are separated by periods.
A relative CDD pathname begins with any generation name other than CDD$TOP and specifies the given names of the descendants after that point. A relative path comes into existence when a default directory is established with a logical name.
In the following example, the logical name definition specifies the beginning of the CDD pathname. So, a relative pathname specifies the remainder of the path to the record definition:
$ DEFINE CDD$DEFAULT CDD$TOP.FOR |
The following examples show how a CDD pathname beginning with CDD$TOP overrides the default CDD pathname. Consider a record with the pathname CDD$TOP.SALES.JONES.SALARY. If you define CDD$DEFAULT to be CDD$TOP.SALES.JONES, you can then specify a relative pathname; for example:
DICTIONARY 'SALARY' |
You can also specify this as a full pathname, for example:
DICTIONARY 'CDD$TOP.SALES.JONES.SALARY' |
On CDD pathnames, see Using CDD/Repository on VMS Systems.
13.2 INCLUDE Statement
The INCLUDE statement directs the compiler to stop reading statements from the current file and read statements in an included file or text module.
The INCLUDE statement takes one of the following forms:
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file-name
Is a character string specifying the name of the file to be included; it must not be a named constant.The form of the file name must be acceptable to the operating system, as described in your system documentation.
/[NO]LIST
Specifies whether the incorporated code is to appear in the compilation source listing. In the listing, a number precedes each incorporated statement. The number indicates the "include" nesting depth of the code. The default is /NOLIST. /LIST and /NOLIST must be spelled completely.text-lib
Is a character string specifying the file name of the text library to be searched.The form of the file name must be acceptable to the operating system, as described in your system documentation.
module-name
Is a character string specifying the name of the text library module to be included. The name of the text module must be enclosed in parentheses. It can contain any alphanumeric character and the special characters dollar sign ($) and underscore (_).The length of the file name must be acceptable to the operating system, as described in your system documentation.
An INCLUDE statement can appear anywhere within a scoping unit. The statement can span more than one source line, but no other statement can appear on the same line. The source line cannot be labeled.
An included file or text module cannot begin with a continuation line, and each Fortran statement must be completely contained within a single file.
An included file or text module can contain any source text, but it cannot begin or end with an incomplete Fortran statement.
The included statements, when combined with the other statements in the compilation, must satisfy the statement-ordering restrictions shown in Figure 2-1.
Included files or text modules can contain additional INCLUDE statements, but they must not be recursive. INCLUDE statements can be nested until system resources are exhausted.
When the included file or text module completes execution, compilation resumes with the statement following the INCLUDE statement.
When including files that contain datatype declarations, it is recommended that such declarations explicitly specify the kind of the datatype. If an explicit kind is omitted, the declarations will be interpreted according to the command-line options in effect when the file is included, which may result in unintended behavior.
In Example 13-1, a file named COMMON.FOR (in the current working directory) is included and read as input.
| Example 13-1 Including Text from a File |
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Main Program File COMMON.FOR File
PROGRAM
INCLUDE 'COMMON.FOR' INTEGER, PARAMETER :: M=100
REAL, DIMENSION(M) :: Z REAL, DIMENSION(M) :: X, Y
CALL CUBE COMMON X, Y
DO I = 1, M
Z(I) = X(I) + SQRT(Y(I))
...
END DO
END
SUBROUTINE CUBE
INCLUDE 'COMMON.FOR'
DO I=1,M
X(I) = Y(I)**3
END DO
RETURN
END
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The file COMMON.FOR defines a named constant M, and defines arrays X and Y as part of blank common.
The OPTIONS statement overrides or confirms the compiler options in effect for a program unit. It takes the following form:
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option
Is one of the following:
- /CHECK =
- ALL
- [NO]BOUNDS
- [NO]OVERFLOW
- [NO]UNDERFLOW
- NONE
- /NOCHECK
- /CONVERT =
- BIG_ENDIAN
- CRAY
- FDX
- FGX
- IBM
- LITTLE_ENDIAN
- NATIVE
- VAXD
- VAXG
- /[NO]EXTEND_SOURCE
- /[NO]F77
- /FLOAT =
- D_FLOAT
- G_FLOAT
- IEEE_FLOAT
- /[NO]G_FLOATING
- /[NO]I4
- /[NO]RECURSIVE
Note that an option must always be preceded by a slash (/).
Some OPTIONS statement options are equivalent to compiler options.
The OPTIONS statement must be the first statement in a program unit, preceding the PROGRAM, SUBROUTINE, FUNCTION, MODULE, and BLOCK DATA statements.
OPTIONS statement options override compiler options, but only until the end of the program unit for which they are defined. If you want to override compiler options in another program unit, you must specify the OPTIONS statement before that program unit.
The following are valid OPTIONS statements:
OPTIONS /CHECK=ALL/F77 OPTIONS /I4 |
On compiler options, see the HP Fortran for OpenVMS User Manual.
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