This manual introduces standard Fortran, supported Fortran extensions, and provides a discussion of flexible file input/output (FFIO) and other input/output (I/O) methods. This manual is for Fortran programmers who need general I/O information or who need information on how to optimize their I/O.
This manual contains the following chapters:
Chapter 2, “Standard Fortran I/O”, discusses elements of the Fortran 95 standard that relate to I/O.
Chapter 3, “Fortran I/O Extensions ”, discusses extensions to the Fortran standard.
Chapter 4, “Named Pipe Support ”, discusses tape handling and FIFO special files.
Chapter 5, “System and C I/O ”, discusses system calls and Fortran callable entry points to C library routines.
Chapter 6, “The assign Environment”, discusses the use of the assign(1) command to access and update advisory information from the I/O library and how to create an I/O environment.
Chapter 7, “File Structures ”, discusses native file structures.
Chapter 8, “Buffering”, discusses file buffering as it applies to I/O.
Chapter 9, “Introduction to FFIO ”, provides an overview of the Flexible File I/O system.
Chapter 10, “Using FFIO ”, describes how to use FFIO with common file structures, and how to use FFIO to enhance program performance.
Chapter 11, “Foreign File Conversion”, discusses how to convert data from one file structure to another.
Chapter 12, “I/O Optimization ”, discusses methods to speed up I/O processing.
Chapter 13, “FFIO Layer Reference ”, provides details about individual FFIO layers.
Chapter 14, “Creating a user Layer ”, provides an example of how to create an FFIO layer.
An error message system is provided that consists of commands, library routines, and files that allow error messages to be retrieved from message catalogs and formatted at run time.
The user who receives a message can request more information by using the explain(1) user command. The explain command retrieves a message explanation from an online explanation catalog and displays it on the standard output device.
The msgid argument to the explain command is the message ID string that appears when an error message is written. The ID string contains a product group code and the message number.
The product group code or product code is a string that identifies the product issuing the message. The product code for the Fortran libraries and for the I/O libraries is lib. The number specifies the number of the message. The following list describes the categories of message numbers:
All Fortran library errors are within the range of 4000-5000. Libraries may also return system error numbers in the range of 1 to the first library error number. You must use the sys product code with numbers in this range.
Flexible file I/O (FFIO) returns error values that are in the range of 5000 to 6000 and have a product code of lib.
Both of the following are variations of the explain command used with a msgid from the Fortran I/O library:
explain lib1100 |
explain lib-1100 |
The previous explain command produces the following description on a standard output file:
explain lib-1100 lib-1100: A READ operation tried to read a nonexistent record. On a Fortran READ statement, the REC (record) specifier was larger than the largest record number for that direct-access file. Check the value of the REC specifier to ensure that it is a valid record number. Check the file being read to ensure that it is the correct file. Also see the description of input/output statements in your Fortran reference manual. The class of the error is unrecoverable (issued by the Fortran run-time library). |
There are two classes of Fortran library error messages: UNRECOVERABLE and WARNING.
The following is an example of a warning message:
lib-1951 a.out: At line <n> in Fortran routine "<name>", in
dimension <d>, extents <e1> and <e2> are not equal.
When bounds checking is enabled, this message is issued if an array
assignment exceeds the bounds of the result array. The line
number <n> in the Fortran routine <name> is where the two array
extents (<el> and <e2>) did not match.
Modify the program so as not exceed the bounds of the array, or
ensure that the array extents are equal.
Also see the description of array operations in your Fortran
reference manual.
Note that this message is issued as a warning. Execution of the
program will continue. |
If the message number is not valid, a message similar to the following appears:
explain: no explanation for lib-3000 |