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Functions.AEvalT Method (Array OfT, ActionT, DWord, DWord)

Execute a code block for each element in an array.

Namespace:  XSharp.RT
Assembly:  XSharp.RT (in XSharp.RT.dll) Version: 2.16
	aArray AS ARRAY OF<T>,
	cbBlock AS Action<T>,
	nStart AS DWORD,
	nCount AS DWORD
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Type: Array OfT
The array to traverse.
Type: ActionT
The code block to execute.
Type: DWord
The starting element.
A negative value starts from the end.
If nCount is positive, the default value is 1; if nCount is negative, the default value is the length of the array.
Type: DWord
The number of elements to process from nStart.
A negative value starts from the end.
The default is all elements to the end of the array.

Type Parameters

The type of the array elements

Return Value

Type: Array OfT
A reference to aArray.
The return value of the code block or is ignored — to assign the return value to each element in the array, use the AEvalA() function.
AEval() passes the element value and the element index as arguments. AEval() makes no assumptions about the contents of the array elements it is passing.
It is assumed that the supplied code block knows what type of data will be in each element. AEval() is similar to DBEval() which executes code for each record of a database file.
Like DBEval(), AEval() can be used as a primitive for the construction of iteration commands for both simple and complex array structures.
Tip Tip
In Visual Objects 2 different functions were introduced: AEval() and AEvalOld(). The difference between these functions was that AEval() was only calling the codeblock with one parameter (the element in the array), where AEvalOld() was also passing in a second parameter (the array index). Inside X# this difference no longer exists. So AEval() and AEvalOld() are doing the same thing in X#.
This example displays the contents of a one-dimensional array:
1LOCAL aArray[6]
2AFill(aArray, "Hi All!") // Fill up all elements
3AEval(aArray, {|Element| QOut(Element)})
This example uses AEval() to display an array of file names and file sizes returned from the Directory() function:
1LOCAL aFiles := Directory("*.dbf")
2LOCAL nTotal := 0
3AEval(aFiles, {|aDBFFile | QOut(PadR(aDBFFile[F_NAME], 10), ;
4        aDBFFile[F_SIZE], nTotal += aDBFFile[F_SIZE]})
5? "Total bytes:", nTotal
See Also