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The graPHIGS Programming Interface : Subroutine Reference

GPQEHA - Inquire List of Element Headers for any Structure

GPQEHA (strid, start, number, errind, actnum, header)

Note:

This subroutine is a Structure State List (SSL) inquiry. For an overview, see "SSL Inquiries"

Purpose

Use GPQEHA to inquire a list of element headers from a specified structure. This subroutine returns the list in sequential order starting from a specified element position.

  • If the specified element position is greater than the number of elements in the structure, then the errind parameter will contain an error.

  • If the specified element position is less than one, the errind parameter will contain an error.

  • If the requested number is larger than the number of elements between the current element and the end of the structure, only information about the existing elements is returned and the actual number (actnum) parameter is set to the number of element codes.

    • If the inquired information is available, then the graPHIGS API sets the error indicator to zero and returns the values in the output parameters. If the inquired information is unavailable, then the error indicator (errind) contains an error number indicating the reason, and the values returned in the output parameters are unpredictable.

    Note:

    The format of the element headers that are returned by this subroutine is the same as that returned by the Inquire List of Element Headers (GPQEHD) subroutine.

    Parameters

    strid -- specified by user, fullword integer

    Structure identifier.

    start -- specified by user, fullword integer

    The position of the first element whose header is to be returned (>=1)

    number -- specified by user, fullword integer

    Number of element headers requested (>=1)

    errind -- returned by the graPHIGS API, fullword integer

    Error indicator. If the error indicator is zero, the request has been completed. Otherwise, one of the following errors exists:
    12
    FUNCTION REQUIRES STATE SSSL
    122
    STRUCTURE IDENTIFIER DOES NOT EXIST
    524
    ELEMENT POSITION > NUMBER OF ELEMENTS IN STRUCTURE
    538
    START VALUE < ONE
    540
    REQUESTED NUMBER < ONE

    actnum -- returned by the graPHIGS API, fullword integer

    Number of element headers actually returned.

    header -- returned by the graPHIGS API, fullword integer

    A list of element headers. The first halfword of each element header contains the length of the element and the second halfword contains the element code. The information that corresponds to each element header and the list of element codes used by graPHIGS API can be found in The graPHIGS Programming Interface: Technical Reference

    Error Codes

    None

    Related Subroutines

    GPQED
    Inquire List of Element Data
    GPQEDA
    Inquire List of Element Data for any Structure
    GPQEHD
    Inquire List of Element Headers

    RCP code

    201337104 (X'0C002910')

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