/sys$common/syshlp/helplib.hlb PASCAL, Input Output, Direct Access, FIND *Conan The Librarian (sorry for the slow response - running on an old VAX) |
The FIND procedure positions a file at a specified component. The file must be open for direct access and must contain fixed-length components. Syntax: FIND( file_variable, component-number [[, ERROR := error-recovery]] ); The 'file_variable' is the name of the file variable associated with a file that is open for direct access. The 'component-number' is a positive integer expression that indicates the component at which the file is to be positioned. If the component number is zero or negative, a run-time error occurs. The 'error-recovery' specifies the action to be taken if an error occurs during execution of the routine. By default, after the first error, the error message is printed and execution is stopped. The FIND procedure allows direct access to the components of a file. You can use the FIND procedure to move forward or backward in a file. After execution of the FIND procedure, the file is positioned at the specified component. The file buffer variable assumes the value of the component, and the file mode is set to inspection. If the file has relative organization, the current file component is locked. If there is no file component at the selected position, the file buffer is undefined (UFB becomes TRUE) and the mode becomes undefined. After any call to FIND, the value of EOF is undefined. You can use the FIND procedure only when reading a file that was opened by the OPEN procedure. If the file is open because of a default open (that is, with EXTEND, RESET, or REWRITE), a call to FIND results in a run-time error because the default access method is sequential. See the "Compaq Pascal Language Reference Manual" for a complete description of the FIND procedure.
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