isopen(S)                      6 January 1993                      isopen(S)


 Name

    isopen - open an ISAM file

 Syntax


    cc  . . .  -lisam


    isopen(filename, mode)
    char *filename;
    int mode;


 Description

    The isopen function opens a data file for processing. The call returns
    the file descriptor that is to be used by subsequent ISAM calls on that
    file.  Use the isclose function to close the file.

    You can use the following arguments with this routine:


    _________________________________________________________________________
    Argument                         Description
    _________________________________________________________________________
    filename                         Null-terminated character string identi-
                                     fying the name of the ISAM file to be
                                     opened.
    mode                             are described below.


    The current index is set to the primary key.

    The current record pointer is set to the first record in the file based
    on the order in the primary index.  It can be set to the first record in
    another index by using the isstart function.

    The mode parameter specifies the lock mode and the read/write mode in
    effect while the file is open.  The value of the mode parameter is the
    arithmetic sum of a lock mode value and a read/write mode value.

    The lock mode values are defined in isam.h as:

    _________________________________________________________________________
    Lock Mode         Description
    _________________________________________________________________________
    ISAUTOLOCK        automatic record lock
    ISMANULOCK        manual record lock
    ISEXCLLOCK        exclusive isam file lock
    ISSHARLOCK        shared isam file lock

    These modes have the following effects:

    +  When ISAUTOLOCK is used, each record is locked when it is read, and
       unlocked after the next function call is made.

    +  When ISMANULOCK is used, the user must manually lock and unlock each
       record to perform any operation on that record.  A record can be
       locked by using the ISLOCK mode in the isread function call, and
       unlocked with the isrelease function call.

    +  When ISEXCLLOCK is used, the entire file is locked. Other users can
       neither read from nor to the file.  The file is automatically unlocked
       when it is closed with isclose.

    +  When ISSHARLOCK is used, the entire file is locked with a shared lock.
       Other users can read the file and place shared locks on it but may not
       change it. The file is automatically unlocked when it is closed with
       isclose.

    The read/write mode values are defined in isam.h as:

    _________________________________________________________________________
    Access Modes               Description
    _________________________________________________________________________
    ISINPUT                    open for reading only
    ISOUTPUT                   open for writing only
    ISINOUT                    open for reading and writing

    On success, isopen returns a non-negative integer.  Otherwise, it returns
    -1 and sets iserrno to indicate the error.

 Example


       isopen( "books", ISAUTOLOCK + ISINOUT ) ;


 See also

    isbuild(S), isclose(S)

 Standards conformance

    isopen is not part of any currently supported standard; it is an exten-
    sion of AT&T System V provided by the Santa Cruz Operation.