What does the To and Step mean in VBA?

Question

Dim i As Long
Dim rows As Long
Dim rng3 As Range
rows = rng3.rows.Count
For i = rows To 1 Step (-1)

Does anyone know how this loop works? I'm confused on the meaning of rows To 1 Step (-1) .

Answer 1

from high number To 1 adding (-1) each iteration

Note: It's adding because + AND - in mathematical logic evaluate to a -

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If rows = 10 then

for i = 10 to 1 step -2 would mean loop back from 10 to 1 subtracting 2 from the i in each loop cycle .

adding a Debug.Print i inside the loop may give you a better clue.

Note: turn ON the Immediate Window hitting CTRL + G or View => Immediate Window from the VBE menu bar

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An example loop increasing by 3 on each cycle.

for i = 1 to 10 step 3
    debug.print i 
next i

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Usage

The step-back technique is mostly used when deleting rows from a spreadsheet.

To see the logic in practice see the following

• How to select and delete every 3rd column

• Delete entire excel column if all cells are zeroed

• Excel VBA - Scan range and delete empty rows

Answer 2

When deleting rows, it is often common practise to start at the end and step backwards, this is so no rows are skipped.

Dim i As Long
Dim rows As Long
Dim rng3 As Range

rows = rng3.rows.Count


For i = rows To 1 Step (-1)

    'delete row if "delete" is in column 1
    If rng3.cells(i,1).Value = "delete" Then

    rng3.Rows(i).EntireRow.Delete

    End If

next i

Answer 3

Dim i as Integer

For i = 1 To 14 Step 3
Debug.Print i
Next i

In above code loop will iterate from 1 to 14 increment with 3 so output will be like

1 4 7 10 13

It means it can not cross 14 that is limit.

So whatever value is provided in step it will add into the variable use for looping purpose. Here

i = i +3

But in For loop in VBA, Step value can not be changed dynamically. For example:

Dim i As Integer

For i = 1 To 10 Step i
    Debug.Print i
Next i

Here, before starting iteration Step is equal to the value of i that is the default value ie 0. So i will increment like below:

i = i+ i => i = i+0

So i will not increment here and loop will iterate for ever.

Now for below code:

Dim i as Integer

For i = 1 To 14 Step i+1
Debug.Print i
Next i

i will increment like :

i=i+(i+1) => i= i+(0+1) =>i = i+1

so it will increment by 1 and output will be 1 2 3 .... 14

Now for below code :

Dim i As Integer
i = 3
For i = 1 To 10 Step i
    Debug.Print i
Next i

here, i is equal to 3 before loop execution, so Step value will be 3, but loop will start with i = 1 and will increment with 3 through out the loop. here,

i = i+3

so output will be 1 4 7 10.

Now for some other variable:

Dim i As Integer
Dim j As Integer
j = 2

For i = 1 To 10 Step j
    Debug.Print i
    j = i
Next i

in above code Step value will be 2, so i will increment by 2 for every iteration whether j is modifying inside loop or not, it will not impact Step value, so output will be

1 3 5 7 9

Please correct me if I miss anything or something is wrong in this. Also suggest if there is any way for dynamic looping using For loop in VBA.