How I can delete an item …

How I can delete an item in an array ?

Short Answer : We have a special function : ADel()
Long Answer :

ADel() function may cause some confusions when documentation not read carefully:

This function deletes the element found at the given subscript position in the array.

All elements in the array below the given subscript position will move up one positionin the array.

 

Let’s try:

?
 aTest1 := { 'One', 'Two', "Tree",'Four' }
 aTest := ACLONE( aTest1 )
 ADel( aTest, 3 )
 ? LEN( aTest )
 AEVAL( aTest, { | c1 | QQOUT( c1, '' ) } ) 
 

Result :
4
One Two Four NIL
Length of array not changed, last item moved up and new last item became NIL.

 

?
 ASIZE( aTest, 3 )
 ? LEN( aTest )
 ?
 AEVAL( aTest, { | c1 | QQOUT( c1, '' ) } )

Result :
3
One Two Four
Length of array changed, last item (NIL) removed

We have another possibility: a new Harbour function:

?
 aTest1 := { 'One', 'Two', "Tree",'Four' }
 aTest := ACLONE( aTest1 )
 HB_ADel( aTest, 3 )
 ? LEN( aTest )
 ?
 AEVAL( aTest, { | c1 | QQOUT( c1, '' ) } )
 

Result :
4
One Two Four NIL
Length of array not changed, last item moved up and new last item became NIL.
Same as ADel()

And we have a third parameter : Shrink or not:

 ?
 aTest1 := { 'One', 'Two', "Tree",'Four' }
 aTest := ACLONE( aTest1 )
 HB_ADel( aTest, 3, .T. )
 AEVAL( aTest, { | c1 | QQOUT( c1, '' ) } )

That’s all !

 

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Harbour All Functions – A

AAdd
Abs
AChoice
AClone
ACopy
ACos

ADays
AddASCII
AddMonth
ADel
ADir
AfterAtNum
AEval
AFields
AFill
AIns
Alert
Alias
AllTrim

AMonths
Array
Asc
AScan
ASCIISum
ASCPos
ASin
ASize
ASort
At
AtAdjust
ATail
ATan
ATn2
AtNum
AtRepl
AtToken

Array Functions

AAdd Dynamically add an element to an array
AClone Duplicate an array
ACopy Copy elements from one array to another
ADel Delete an element form an array
AEval Evaluates the subscript element of an array
AFill Fill an array with a specified value
AIns Insert a NIL value at an array subscript position
Array Build an uninitialized array of specified length
AScan Scan array elements for a specified condition
ASize Adjust the size of an array
ASort Sort an array
ATail Returns the rightmost element of an array

ASize()

 

ASIZE()

Adjust the size of an array

Syntax

      ASIZE(<aArray>, <nLen>) --> aTarget

Arguments

<aArray> Name of array to be dynamically altered

<nLen> Numeric value representing the new size of <aArray>

Returns

<aTarget> an array pointer reference to <aTarget>.

Description

This function will dynamically increase or decrease the size of <aArray> by adjusting the length of the array to <nLen> subscript positions.

If the length of the array <aArray> is shortened, those former subscript positions are lost. If the length of the array is lengthened a NIL value is assigned to the new subscript position.

Examples

      LOCAL aArray := { 1 }      // Result: aArray is { 1 }
      ASize( aArray, 3 )         // Result: aArray is { 1, NIL, NIL }
      ASize( aArray, 1 )         // Result: aArray is { 1 }

Compliance

If HB_COMPAT_C53 is defined, the function generates an Error, else it will return the array itself.

Files

Library is vm

Seealso

AADD(), ADEL(), AFILL(), AINS()

Array()

 

ARRAY()

Create an uninitialized array of specified length

Syntax

      ARRAY( <nElements> [, <nElements>...] ) --> aArray

Arguments

<nElements> is the number of elements in the specified dimension.

Returns

<aArray> an array of specified dimensions.

Description

This function returns an uninitialized array with the length of <nElements>.

Nested arrays are uninitialized within the same array pointer reference if additional parameters are specified.

Establishing a memory variable with the same name as the array may destroy the original array and release the entire contents of the array. This depends, of course, on the data storage type of either the array or the variable with the same name as the array.

Examples

      PROCEDURE Main()
         LOCAL aArray := Array( 10 )
         LOCAL x
         FOR x := 1 TO Len( aArray )
            aArray[ x ] := Array( x )
         NEXT
         // Result is: { { NIL }, { NIL, NIL }, ... }
         RETURN

Compliance

Clipper (array)

Files

Library is vm

Seealso

AADD(), ADEL(), AFILL(), AINS()

AIns()

 

AINS()

Insert a NIL value at an array subscript position.

Syntax

      AINS( <aArray>, <nPos> ) --> aTarget

Arguments

<aArray> Array name.

<nPos> Subscript position in <aArray>

Returns

<aTarget> an array pointer reference.

Description

This function inserts a NIL value in the array named <aArray> at the <nPos>th position.

All array elements starting with the <nPos>th position will be shifted down one subscript position in the array list and the last item in the array will be removed completely. In other words, if an array element were to be inserted at the fifth subscript position, the element previously in the fifth position would now be located at the sixth position. The length of the array <aArray> will remain unchanged.

Examples

      LOCAL aArray := { "Harbour", "is", "Power!", "!!!" }
      AIns( aArray, 4 )

Compliance

Clipper

Files

Library is vm

Seealso

AADD(), ACOPY(), ADEL(), AEVAL(), AFILL(), ASIZE()

ACopy()

ACOPY()

Copy elements from one array to another

Syntax

      ACOPY( <aSource>, <aTarget>, [<nStart>], [<nCount>], [<nTargetPos>] ) --> aTarget

Arguments

<aSource> is the array to copy elements from.

<aTarget> is the array to copy elements to.

<nStart> is the beginning subscript position to copy from <aSource>

<nCount> the number of subscript elements to copy from <aSource>.

<nTargetPos> the starting subscript position in <aTarget> to copy elements to.

Returns

<aTarget> an array pointer reference

Description

This function copies array elements from <aSource> to <aTarget>.

<nStart> is the beginning element to be copied from <aSource>; the default is 1.

<nCount> is the number of elements to be copied from <aSource>; the default is the entire array.

<nTargetPos> is the subscript number in the target array, <aTarget>, to which array elements are to be copied; the default is 1

This function will copy all data types in <aSource> to <aTarget>.

If an array element in <aSource> is a pointer reference to another array, that array pointer will be copied to <aTarget>; not all subdimensions will be copied from one array to the next. This must be accomplished via the ACLONE() function.

Note: If array <aSource> is larger then <aTarget>, array elements will start copying at <nTargetPos> and continue copying until the end of array <aTarget> is reached. The ACOPY() function doesn’t append subscript positions to the target array, the size of the target array <aTarget> remains constant.

Examples

      LOCAL nCount := 2, nStart := 1, aOne, aTwo
      aOne := { "HARBOUR", " is ", "POWER"}
      aTwo := { "CLIPPER", " was ", "POWER"}
      ACopy( aOne, aTwo, nStart, nCount )

Compliance

Clipper

Files

Library is vm

Seealso

ACLONE(), ADEL(), AEVAL(), AFILL(), AINS(), ASORT()