Cascade Historian: Version 4.1
Prev |  | Next

# length

length -- finds the total number of values in a history.

## Syntax

    (length history [start [end]])

## Parameters

`history`

  The name of a history defined by the history command.

`start`

  Optional, the start of a desired time range in seconds, expressed as a real number. The default is the first value available.

`end`

  Optional, the end of a desired time range in seconds, expressed as a real number. The default is the last value available.

## Returns

An integer number of values in the history between the specified start and end times, in this format:

        (length history length)

on success, otherwise:

        (error "History history does not exist")

## Description

This command queries the history for the total number of values available.

This command corresponds to the Cogent API function `HI_Length` and the `hist_length` dynamic library function.

## Example

        [sh]$ lsend Hist
        Hist> (length p3)
        (length p3 2853)
        Hist> (length p3 973632000.500 973636000.500)
        (length p3 11)
        Hist>

Prev | Home | Next
latest | Up | list

Copyright 1995-2002 by Cogent Real-Time Systems, Inc.