InsertImage (Stringlist function): Difference between revisions

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m (consistent example formatting)
m (consistent example formatting)
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<p class="code">image cust
<p class="code">image cust
  ssn is string len 10
<p class="code">ssn is string len 10
  name is string len 20
name is string len 20
  bdate is string len 8
bdate is string len 8
</p>
end image
end image


find records to %recset
find records to %recset
  name = smith
<p class="code">name = smith
</p>
end find
end find


for each record in %recset
for each record in %recset
  %cust:ssn = ssn
<p class="code">%cust:ssn = ssn
  %cust:name = name
%cust:name = name
  %cust:bdate = bdate
%cust:bdate = bdate
  for %i from 1 to %list:count
for %i from 1 to %list:count
      if %cust:ssn lt %list:item(%i, 1, 10) then
  if %cust:ssn lt %list:item(%i, 1, 10) then
        loop end
      loop end
      end if
  end if
  end for
end for
  %list:insertImage(%i, 'CUST')
%list:insertImage(%i, 'CUST')
</p>
end for
end for
</p>
</p>
Line 52: Line 55:
<p class="code">%list:bindImage('CUST')
<p class="code">%list:bindImage('CUST')
for each record in %recset
for each record in %recset
  ...
<p class="code">...
  %list:insertImage(%i)
%list:insertImage(%i)
</p>
end for
end for
</p>
</p>

Revision as of 22:35, 6 February 2011

Insert image into a Stringlist (Stringlist class)


This callable method inserts data from an image into a Stringlist at a specific location.

Syntax

[%count =] sl:InsertImage( itemNum, [imageName])

Syntax terms

%count A numeric variable to contain the number of items in sl after the image has been inserted.
sl A Stringlist object.
itemNum The item number before which the image is to be inserted. If itemNum is 1, the image is inserted before the first item in the sl Stringlist. If itemNum is equal to the number of items in the Stringlist plus one, the image is added after the last sl item (the same effect as an AddImage invocation). This is a required argument, and it must have a value between 1 and the number of items in sl plus 1, inclusive.
imageName A string that contains the name of an image. This is an optional argument if an image has already been associated with the Stringlist via BindImage. Otherwise, it is a required argument.

Usage notes

  • All errors in InsertImage result in request cancellation.
  • InsertImage can result in the splitting of a Stringlist leaf page. Once a leaf page is split, it will not be merged back together again, even if subsequent RemoveImage invocations make this possible. Because of this splitting, heavy use of Insert, InsertImage and/or RemoveImage can result in "sparse" Stringlists which place an unnecessary burden on the buffer pool and CCATEMP. It can also result in an inability to add an item to the end of the stringlist (via Add) because of a full pointer page, even though the stringlist is nowhere near the theoretical capacity for a stringlist. To make matters worse, Copy does a page-for-page copy of a stringlist, so it does not result in any compression of the resultant stringlist. stringlist compression can be achieved using CopyItems.

Examples

  1. One application of InsertImage is to create a large sorted array, although this can also (and more efficiently) be achieved with Sort or SortNew. The following example demonstrates how such a mechanism might be used, to order Stringlist items by SSN:

    image cust

    ssn is string len 10 name is string len 20 bdate is string len 8

    end image

    find records to %recset

    name = smith

    end find

    for each record in %recset

    %cust:ssn = ssn %cust:name = name %cust:bdate = bdate for %i from 1 to %list:count if %cust:ssn lt %list:item(%i, 1, 10) then loop end end if end for %list:insertImage(%i, 'CUST')

    end for

  2. The above example can be made neater and more efficient by coding the InsertImage as follows:

    %list:bindImage('CUST') for each record in %recset

    ... %list:insertImage(%i)

    end for

    In this example, BindImage associates the image with the Stringlist, eliminating the need to specify the image name on the InsertImage invocation.

See also