Это хорошо документированное поведение PHP. См. предупреждение на странице foreach php.net
Warning
Ссылка на $ value , а последний элемент массива остается даже после цикла foreach . Рекомендуется уничтожить его unset ().
$a = array('a', 'b', 'c', 'd'); foreach ($a as &$v) { } unset($v); foreach ($a as $v) { } print_r($a);
EDIT
Попытайтесь пошаговое руководство к тому, что на самом деле происходит здесь
$a = array('a', 'b', 'c', 'd'); foreach ($a as &$v) { } // 1st iteration $v is a reference to $a[0] ('a') foreach ($a as &$v) { } // 2nd iteration $v is a reference to $a[1] ('b') foreach ($a as &$v) { } // 3rd iteration $v is a reference to $a[2] ('c') foreach ($a as &$v) { } // 4th iteration $v is a reference to $a[3] ('d') // At the end of the foreach loop, // $v is still a reference to $a[3] ('d') foreach ($a as $v) { } // 1st iteration $v (still a reference to $a[3]) // is set to a value of $a[0] ('a'). // Because it is a reference to $a[3], // it sets $a[3] to 'a'. foreach ($a as $v) { } // 2nd iteration $v (still a reference to $a[3]) // is set to a value of $a[1] ('b'). // Because it is a reference to $a[3], // it sets $a[3] to 'b'. foreach ($a as $v) { } // 3rd iteration $v (still a reference to $a[3]) // is set to a value of $a[2] ('c'). // Because it is a reference to $a[3], // it sets $a[3] to 'c'. foreach ($a as $v) { } // 4th iteration $v (still a reference to $a[3]) // is set to a value of $a[3] ('c' since // the last iteration). // Because it is a reference to $a[3], // it sets $a[3] to 'c'.
Для теории см. здесь (следуйте ссылкам!). Практическая демонстрация
recordset:
Option Explicit
Const adInteger = 3 ' 00000003
Const adVarChar = 200 ' 000000C8
Dim sInp : sInp = "Z1,Z3,Z2,Z20,Z10"
Dim aInp : aInp = Split(sInp, ",")
WScript.Echo "A:", Join(aInp)
Dim oRS : Set oRS = CreateObject("ADODB.Recordset")
oRS.Fields.Append "Word", adVarChar, 50
oRS.Fields.Append "Length", adInteger
oRS.Open
Dim sWord
For Each sWord In aInp
oRS.AddNew
oRS.Fields("Word").value = Left(sWord, 1)
oRS.Fields("Length").value = CInt(Mid(sWord, 2))
oRS.UpDate
Next
oRS.Sort = "Word, Length"
Dim aTable : aTable = oRS.GetRows()
ReDim aOut(UBound(aTable, 2))
Dim i
For i = 0 To UBound(aOut)
aOut(i) = aTable(0, i) & aTable(1, i)
Next
WScript.Echo "B:", Join(aOut)
ArrayList
Option Explicit
Dim sInp : sInp = "Z1,Z3,Z2,Z20,Z10,E1,D3,C2,B20,A10"
Dim aInp : aInp = Split(sInp, ",")
WScript.Echo "A:", Join(aInp)
Dim oNAL : Set oNAL = CreateObject( "System.Collections.ArrayList" )
Dim oSB : Set oSB = CreateObject( "System.Text.StringBuilder" )
Dim sWord
For Each sWord In aInp
oSB.AppendFormat_2 "{0}{1,4}", Left(sWord, 1), CInt(Mid(sWord, 2))
sWord = oSB.ToString()
oSB.Length = 0
oNAL.Add sWord
Next
oNAL.Sort
ReDim aOut(oNAL.Count - 1)
Dim i
For i = 0 To UBound(aOut)
aOut(i) = Left(oNAL(i), 1) & CInt(Mid(oNAL(i), 2))
Next
WScript.Echo "B:", Join(aOut)