Add item to array in VBScript

Question

How do you add an item to an existing array in VBScript   Is there a VBScript equivalent to the push function in Javascript   i e   myArray has three items   Apples    Oranges   and  Bananas  and I want to add  Watermelons  to the end of the array

User · Answer

For your copy and paste ease    add item to array Function AddItem arr  val      ReDim Preserve arr UBound arr    1      arr UBound arr     val     AddItem   arr End Function   Used like so  a   Array   a   AddItem a  5  a   AddItem a   foo

User · Answer

Slight change to the FastArray from above    pushtest vbs imax   10000000 value    Testvalue  s   imax  amp    of      amp  value  amp         t0   timer  Fast array a   array   ub   UBound a  For i   0 To imax  If i gt ub Then      ReDim Preserve a Int  ub 10  1 1       ub   UBound a   End If  a i    value Next ReDim Preserve a i-1  s   s  amp    FastArr    amp  FormatNumber timer - t0  3  -1   amp       MsgBox s   There is no point in checking UBound a  in every cycle of the for if we know exactly when it changes   I ve changed it so that it checks does UBound a  just before the for starts and then only every time the ReDim is called  On my computer the old method took 7 52 seconds for an imax of 10 millions   The new method took 5 29 seconds for an imax of also 10 millions  which signifies a performance increase of over 20   for 10 millions tries  obviously this percentage has a direct relationship to the number of tries

User · Answer

Not an answer Or Why  tricky  is bad    gt  gt  a   Array 1   gt  gt  a   Split Join a         amp     2          gt  gt  WScript Echo a 0    a 1   gt  gt  12

User · Answer

this some kind of late but anyway and it is also somewhat tricky    dim arrr    arr  array   Apples    Oranges    Bananas    dim temp var   temp var   join  arr           some character which will not occur is regular strings   if len temp var   gt  0 then    temp var   temp var amp    Watermelons   end if  arr    split temp var           here you got new elemet in array    for each x in arr response write x  amp    lt br   gt    next     review and tell me if this can work  or initially  you save all data in string and later split for array

User · Answer

There are a few ways  not including a custom COM or ActiveX object   ReDim Preserve Dictionary object  which can have string keys and search for them ArrayList  Net Framework Class  which has many methods including  sort  forward  reverse  custom   insert  remove  binarysearch  equals  toArray  and toString   With the code below  I found Redim Preserve is fastest below 54000  Dictionary is fastest from 54000 to 690000  and Array List is fastest above 690000  I tend to use ArrayList for pushing because of the sorting and array conversion   user326639 provided FastArray  which is pretty much the fastest   Dictionaries are useful for searching for the value and returning the index  i e  field names   or for grouping and aggregation  histograms  group and add  group and concatenate strings  group and push sub-arrays    When grouping on keys  set CompareMode for case in sensitivity  and check the  exists  property before  add -ing   Redim wouldn t save much time for one array  but it s useful for a dictionary of arrays    pushtest vbs imax   10000 value    Testvalue  s   imax  amp    of      amp  value  amp         t0   timer  ArrayList Method Set o   CreateObject  System Collections ArrayList   For i   0 To imax   o Add value Next s   s  amp    AList    amp  FormatNumber timer - t0  3  -1   amp      Set o   Nothing  t0   timer  ReDim Preserve Method a   array   For i   0 To imax   ReDim Preserve a UBound a    1    a UBound a     value Next s   s  amp    ReDim    amp  FormatNumber timer - t0  3  -1   amp      Set a   Nothing  t0   timer  Dictionary Method Set o   CreateObject  Scripting Dictionary   For i   0 To imax   o Add i  value Next s   s  amp    Dictionary    amp  FormatNumber timer - t0  3  -1   amp      Set o   Nothing  t0   timer  Standard array Redim a imax  For i   0 To imax   a i    value Next s   s  amp    Array    amp  FormatNumber timer - t0  3  -1   amp       amp  vbCRLF Set a   Nothing  t0   timer  Fast array a   array   For i   0 To imax  ub   UBound a   If i gt ub Then ReDim Preserve a Int  ub 10  1 1    a i    value Next ReDim Preserve a i-1  s   s  amp    FastArr    amp  FormatNumber timer - t0  3  -1   amp      Set a   Nothing  MsgBox s     10000 of  Testvalue   ArrayList 0 156  Redim 0 016  Dictionary 0 031  Array 0 016  FastArr 0 016     54000 of  Testvalue   ArrayList 0 734  Redim 0 672  Dictionary 0 203  Array 0 063  FastArr 0 109    240000 of  Testvalue   ArrayList 3 172  Redim 5 891  Dictionary 1 453  Array 0 203  FastArr 0 484    690000 of  Testvalue   ArrayList 9 078  Redim 44 785  Dictionary 8 750  Array 0 609  FastArr 1 406   1000000 of  Testvalue   ArrayList 13 191  Redim 92 863  Dictionary 18 047  Array 0 859  FastArr 2 031

User · Answer

Arrays are not very dynamic in VBScript  You ll have to use the ReDim Preserve statement to grow the existing array so it can accommodate an extra item   ReDim Preserve yourArray UBound yourArray    1  yourArray UBound yourArray      Watermelons

User · Answer

Based on Charles Clayton s answer  but slightly simplified       add item to array Sub ArrayAdd arr  val      ReDim Preserve arr UBound arr    1      arr UBound arr     val End Sub   Used like so  a   Array   AddItem a  5  AddItem a   foo

[arrays] Add item to array in VBScript

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