Understanding Variables, Conditions & Loops in VBA [Part 2 of 5]

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This article is part of our VBA Crash Course. Please read the rest of the articles in this series by clicking below links.

What are Variables, Conditions & Loops are and how to use them in Excel VBA

  1. What is VBA & Writing your First VBA Macro in Excel
  2. Understanding Variables, Conditions & Loops in VBA
  3. Using Cells, Ranges & Other Objects in your Macros
  4. Putting it all together – Your First VBA Application using Excel
  5. My Top 10 Tips for Mastering VBA & Excel Macros

In part 2 of our VBA Crash Course, we are going to learn what Variables, Conditions & Loops are and how to use them in Excel VBA.

What are Variables, Conditions & Loops?

If you are new to computer programming, you might think I am speaking legalese. So, to make it easy to understand, lets assume you run a bunch of stores across the town. To make it colorful, lets call your stores “We are nuts” – a dry fruit and nuts store chain. At the end of every day, you call each of the 24 store managers and ask them how much sales they have made in that day.

Now, you are not the kind of boss who micro-manages & nitpicks. So you don’t really note down sale for every store. Instead, as you call the store manager, you just mentally update the total. So first store says “$2,300” your total is 2300. Second manger says “$4,000”, the total now will be 6300. So on.

The value 6300 here is nothing but a variable.

A Variable is a small chunk of computer’s memory used to store a value.

Although you don’t micro-manage, you are certainly concerned, whenever a “we are nuts” store reports sales that are too low or too high. You then speak with the store manager for few extra minutes to understand what is going and how you can help. Lets just say, this threshold is $500 for low sales and $5000 for high sales. So anytime a manager reports values beyond this limit (500,5000), you spend some time discussing the business and learning what is going on.

This sort of thing is nothing but a condition.

A Condition is a logical check computer performs to test something. For eg. Sales < 500 or Sales > 5000 is a condition.

And now the whole process of each of the 24 store managers calling you and reporting the daily sales is nothing but a loop. They call you everyday and do the same thing.

A Loop is a set of instructions meant to be followed certain number of times.

Understanding Variables, Conditions & Loops in Excel VBA [Part 2 of 5]

Using Variables in VBA

Variables as we learned, are small chunks of computer memory used to store and retrieve a value. We can use them to store numbers, text, ranges of cells, charts or pretty much anything when it comes to VBA.

As with anything else, Variables too have a life span. Some variables die as soon as the SUB in which they are created ends. Some variables (declared at module level) have better life span as they go to gym and eat healthy food.

How to create variables in VBA?

Whenever you want to use a variable, you must create them first. This is your way of telling computer to set aside some memory units so that your variable can be used.

In Excel VBA, you can do this by the DIM statement.

For eg. below are some variables declared in VBA.

Dim someNumber As Integer
Dim otherNumber As Double
Dim someText As String
Dim aCondition As Boolean
Dim myCells As Range
Dim myChart As Chart
Dim myList(1 To 10) As String
Dim anotherList() As Variant

Aside: Should I define my variables?

By default, you can use variables without defining them in VBA. That means, if we write someNumber=12 without writing any DIM statement corresponding to it, your VBA code would still work. But this is not a good practice. Mainly because, if you are not declaring variables, then you don’t know what is available for you to use.

You can force Excel to throw up an error whenever you did not declare variables by adding the statement option explicit at the top of your code.

As you can see, this is almost like plain English. Let us understand 2 of these lines. The rest you can figure out easily.

Dim someNumber as Integer: This line tells Excel that you want to have a variable with the name someNumber which is of the type Integer. This means, you are going to use someNumber variable to store integer values only. Please note that Excel VBA integers are capable of storing values from -32,768 to 32,767 only. If you want to store bigger (or smaller) numbers, you can use the types Long or Double.

Dim myList(1 to 10) as String: This line tells Excel that you want to use a list of values (called as arrays in computer lingo) of String (text) type. The list size is defined to be 10. You can access individual items of the list by using the item number, like this: myList(2) points to second item in the list.

How to use variables in VBA?

Once you have created a few variables, you can use them in your VBA code. A few examples below.

VBA Code What it does?
someNumber = 2 Stores 2 in to the variable someNumber
someText = “Hello” someText has the text value hello
someNumber = someNumber + 1 Increments the value of someNumber by 1
myList(2) = 812 Sets the value of 2nd item in myList array to 812
activeCell.Value = someNumber Places the value of someNumber in currently selected cell
someNumber = activeCell.Value Places the value of currently selected cell in someNumber variable

Using Conditions in VBA

Almost everything we do involves making decisions & testing conditions. In the “we are nuts” example, we are testing the condition of sales less than 500 or more than 5000 and then doing something based on that.

You can use various statements in VBA to test for conditions. We will learn the simplest of them. IF and THEN statement.

Using IF THEN Statement in VBA

VBA’s IF Then statement looks almost like plain English. Here is an example to test the Sales condition.

If ourSales < 500 or ourSales > 5000 then

'special instructions to handle too many or too little sales

end if

The above code should be obvious to you by now.

Using ELSE statement in VBA

Just like IF THEN statements are used to test a condition and do something, ELSE is used to do something when the IF condition is failed.

For eg,

If ourSales < 500 or ourSales > 5000 then

'special instructions to handle too many or too little sales

Else

'Note down the sales & move on

end if

Would just note down the sales figures if the sales are between 500 and 5000.

Using Loops in VBA

A Loop is a set of instructions meant to be followed specific number of times, as defined earlier. In “we are nuts” example, we are calling and asking for sales 24 times. That means we are doing the same set of operations (call, ask for sales, if the sales are too low or too high do something, hang-up) 24 times, in a loop.

In VBA, there are several different ways to write loops. We will see the easiest type of loop today. For more, please consider joining our Online VBA classes.

Using FOR Loop in VBA

A for loop repeats a set of VBA instructions any given number of times. For eg.

For storeNumber = 1 to 24

'call the store

'ask for sales figures

'do something if needed

'hang up

Next storeNumber

Would run for 24 times and each time repeats the same 4 steps (call, ask, do, hang-up).

Using FOR EACH Loop in VBA

FOR EACH is a special type of loop in Excel used to run same instructions for each of the various items in a list.

For example,

For Each cell in Range("A1:A10")

cell.value = cell.value + 1

Next cell

would run 10 times and increment each of the cell’s values by 1 in the range A1:A10.

Putting it all together – a Simple VBA Program to Note Down Sales of 24 stores

Now that you have learned 3 key ingredients of VBA – Variables, Conditions & Loops, its time we put them together to do a small VBA program.

A Demo of our Daily Sales Log VBA Application

Before we jump in to the code, lets just take a look at how it would work. I have shown it only for 5 stores. But it works for 24.

Using Variables, Conditions & Loops in Excel VBA - A demo

The Code behind our Daily Sales Log VBA Application

Here is the code that captures the sales of 24 stores whenever you click on the “Capture Sales” button.

Sub captureSales()
'when you run this macro, it will take the sales of all the 24 stores we own
'it will ask for a reason if the sales are too low or too high

Dim storeNum As Integer
Dim reason As String
Dim store As Range

storeNum = 1
For Each store In Range("C7:C30")
store.Value = InputBox("Sales for Store " & storeNum)
If store.Value < 500 Or store.Value > 5000 Then
reason = InputBox("Why are the sales deviated?", "Reason for Deviation", "Reason for Deviation")
store.Offset(, 1).Value = reason
End If
storeNum = storeNum + 1
Next store
End Sub

How this code works?

By now, you are already familiar with various parts of this code. So I will just explain the alien portions.

  • Dim statements: These lines declare the variables we are going to use. Notice the different data types (Integer, Range etc.) we have used for various types of data we want to hold.
  • For Each store In Range(“C7:C30”): This line is going to tell excel that for each store (ie cell) in the range C7:C30, we need to repeat the instructions all the way until Next Store. In our case, Excel is going to repeat for 24 times.
  • store.Value = InputBox(“Sales for Store ” & storeNum): This line shows a small box to you and asks for your input. You can enter a number and press OK (or enter). Whatever value you enter will be placed in current store’s cell.
  • reason = InputBox(“Why are the sales deviated?”, “Reason for Deviation”, “Reason for Deviation”): This line shows a box to user with a title and default value (Reason for deviation).
  • store.Offset(,1).value = reason: This statement places the reason for sales deviation in to the cell right to the store sales. Offset(,1) does the trick here.

Download Example Workbook & Learn about Variables, Conditions & Loops in VBA

Click here to download the example workbook and learn more about variables, conditions & loops in VBA.

What Next – Understanding Cells, Ranges & Other Objects in VBA

In the part 3 of this tutorial, learn how to use cells, ranges & other objects from VBA. Stay Tuned.

If you have not read, please read the first part of this series – Introduction to Excel VBA – What is it & How to write your first VBA Macro.

How do you like this Example?

How do you like the VBA examples shown in this article? How would you enhance the macro to do more? One idea is to add another button to clear previous day’s sales.

Please share your views & ideas using comments. I like to learn from what you share.

Join Our VBA Classes

We run an online VBA (Macros) Class to make you awesome. This class offers 20+ hours of video content on all aspects of VBA – right from basics to advanced stuff. You can watch the lessons anytime and learn at your own pace. Each lesson offers a download workbook with sample code. If you are interested to learn VBA and become a master in it, please consider joining this course.

Click here to learn more and Join our VBA program.

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13 Responses to “Gantt Box Chart Tutorial & Template – Download and Try today”

  1. Oli says:

    Hi Chandoo

    As one of your students I have followed your detailed example through with great success. However, Excel is acting in an unexpected way and I wonder if you could take a look?
    http://cid-95d070c79aef808e.office.live.com/self.aspx/.Public/Gantt%20Box%20Chart.xlsm
    On my version, I have to type 40239 (Which equates to 2 Mar 2010) to get the chart to display 31 May 2010 (which should be 40329)!!??

    Have I done something wrong or is Excel acting up?

    Thx
    Oli
    PS Your example file in 2007 displays correctly.

  2. Dave says:

    Hi,

    I like this idea a lot, but I agree the name is a little drab.

    As an American I may just be seeing things, but to me the combination of lines and bars on your chart looks like a bunch of cricket bats.

    Maybe you could work that into a catchier name. 🙂

    Cheers!

  3. Bob says:

    Here is some code I use to keep the axis synched.
    It may be useful to some of your readers
    It is based on a comment I saw on Daily Dose of Excel.

    Function SynchGanttAxis(Cname, lower, upper)
    'Sets the X min and X max for Category axis

    Application.Volatile

    On Error Resume Next
    '
    'Top Horizontal Axis
    With ActiveSheet.Shapes(Cname).Chart.Axes(xlCategory, 1)
    .MinimumScale = lower
    .MaximumScale = upper
    End With

    'Bottom Horizontal Axis
    With ActiveSheet.Shapes(Cname).Chart.Axes(xlValue, 2)
    .MinimumScale = lower
    .MaximumScale = upper
    End With

    End Function

    Function SynchVerticalAxis(Cname, lower, upper)
    Application.Volatile
    On Error Resume Next
    ' Excel 2007 only
    'Right hand vertical axis
    With ActiveSheet.Shapes(Cname).Chart.Axes(xlValue, 1)
    .MinimumScale = 0
    .MaximumScale = upper
    End With

    End Function

  4. Chandoo says:

    @Oli.. Can you check your file again.. I see 40329...

    @Dave: Even I saw things.. the bars actually looked like lollipops. How about calling this lollipop chart - now that would be yummy and goes along the tradition of naming charts after eatables (bar, pie, donut...)

    @Bob: Superb stuff... thanks for sharing 🙂

  5. Mike H says:

    Hi Chandoo
    This looks really good and I think it can also be applied to show project phases / milestones.

    Question: Thinking further could this be amended to display a project lifecycle (Idea through to Implementation say 7 phases) on one bar / row? Just imagine 20 projects within a programme all on one chart one bar each showing their respective lifecycle stages i.e. on one page.

    Idea: As the Gantt Box Chart this is quite intensive to set up re formatting etc how about the added extra of once you have completed this to "Save as template" i.e. saves the formatting and layout of the chart as a template so you can apply to future charts. Simple to do and will save the time formatting etc again and again and again.
    Therefore tip: Click on your chart demo and then click on Save As template icon (2007) - edit file name and click on save. Ready to use / apply via Templates in Change Chart Type window.

    Thanks and be very interested if the lifecycle question can be resolved

    Mike

  6. Oli says:

    How embarrassing.

    I was obviously suffering from numerical dyslexia. I was one of those days.

  7. Chandoo says:

    @Mike H: You can easily make this chart to work like a generic project lifecycle plan chart. All you have to do is,

    1. in a separate sheet define the steps of lifecycle and various dates in a table (with 5 columns for each of the projects you have).
    2. now use a control cell to input the project name you want to show in the chart
    3. based on the input, use OFFSET Formulas to get the correct data
    4. Rest is same as the tutorial above

    For more info on the dynamic charting visit http://chandoo.org/wp/tag/dynamic-charts/ and http://chandoo.org/wp?s=OFFSET

  8. Your solution is really smart but in the en Excel isn't meant to do stuff like this. I, as a former PM, always thought is was frustrating that you had to do stuff like this for something simple like a Gantt chart. So I built Tom's Planner. And would like to plug it here. I think it really solves the problem you are trying to solve in the most efficient way. Check out http://www.tomsplanner.com for a free account or play around with the demo.

  9. Lopi says:

    Hi there,
    Chandoo - this is really a very nice and helpfull chart - I adopted it, so I can report a forecast or the delay of a certain task (coming from my role as an auditor for projects).
    One topic I´m currently struggeling with: I do have a project lasting for lets say 12 month. For a management reporting, I want to have kind of snapshot, lets say one month back and 2 month in the future. I tried with the offset formula, but failed. Any idea?
    Thx
    Lopi

  10. [...] Ein viel geliebter Klassiker ist die Erstellung von GANTT-Diagrammen mit Excel. Wir hatten das Thema wiederholt schon hier. Chandoo.org hat sich mal wieder mit einer neuen Variante hervorgetan: Das GANTT-Box-Chart. [...]

  11. David says:

    Hi Chandoo - fantastic xls. One thing I can't figure out how to do is adjust the alignment of the vertical axis. I would like to left align so that I could indent to represent sub tasks. Can that be done? Or is there a better way?

  12. Paul says:

    I've been trying to work out if there's a way to show weekends on the graph. The closest thing I've got is to add them on a secondary axis, but then I haven't been able to keep both axis lined up together! Any ideas?

    Following on from this - is it possible to show things like holidays?

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