Excel Training VBA Lesson 12

Effective Decision Making With IF OR AND

Effective Decision Making

IF Else And Or Not If

The "If" Function in VBA for Excel is very similar to the "IF" function used in a Worksheet formula. It will return either True or False and it does no more or less than this.  As with the "IF" used in the Worksheet formula the "If" in VBA can take up to two arguments, one for True and one for False. So the syntax for the "If" is simply:

If <Condition to check> Is True Then

'Do one thing

Else

'Do another thing

End If

So this same Function used in a realistic way could be

Sub TheIfFunction()

If Range("A1").Value > 100 Then

Range("B1").Value = 50 + Range("A1").Value

Else

Range("B1").Value = 100

End If

End Sub

This is telling Excel that If the Value of A1 is greater than 100 (True) then change the Value of B1 to the Value of A1 plus another 50, Else (False) changes the Value of B1 to 100. This would be the "If" Function used in it's simplest form. Once Excel encounters the "If" Function it will check the Value of A1, if the value is greater than 100 it will enter into the True argument:

Range("B1").Value = 50 + Range("A1").Value

From there it will Exit the "If" or in other words it will skip the False argument:

Range("B1").Value = 100

But lets assume we wanted Excel to check if Range A1 is equal to 500 first and only go on if it's not (False), to achieve this we would need to extend the "If" so it will possibly check two conditions before exiting the remainder of the "If". This is how we could do this:

Sub TheIfFunction()

If Range("A1").Value = 500 Then

Range("C1").Value = 100 - Range("A1").Value

ElseIf Range("A1").Value > 100 Then

Range("C1").Value = 50 + Range("A1").Value

Else

Range("B1").Value = 100

End If

End Sub

This Function is saying that, If  Range A1 is  equal to 500 (True) then:

Range("C1").Value = 100 - Range("A1").Value

But If Range A1 is NOT equal to 500 then check another condition, which is:

ElseIf Range("A1").Value > 100 Then

If this is True then:

Range("C1").Value = 50 + Range("A1").Value

Finally if neither of these conditions are True then:

Range("B1").Value = 100

We could in theory keep adding an unlimited amount of "ElseIf" Functions to check for multiple conditions. The problem with this is that our "If" Function would become almost impossible to read and more importantly, decipher. I will show you a much better method soon for checking multiple conditions, but for now we will stick with the "If" Function.

There are two other common Keywords used in conjunction with the "If" Function, they are the "And" and the "Or" Operators. We will look first at the "And" operator.

The "And" operator is use to perform a conjunction of two conditions. Whenever we use the "And" operator with the "If" Function it will only ever return True if BOTH conditions are met (True and True). So if we used the "If" combined with the "And" like below:

Sub TheIfAndFunction()

If Range("A1").Value > 100 And Range("A1").Value < 500 Then

Range("B1").Value = Range("A1").Value

End If

End Sub

This would tell Excel that If Range A1 is between 100 and 500 (True) then make:

Range("B1").Value = Range("A1").Value

If  Range A1 is Not between 100 and 500 do nothing. We could again add an unlimited amount of  "And" operators all checking different conditions, but again this would become very hard to decipher and is also not very efficient.

The other common Operator used with the "If" Function is the "Or" Operator. This will check if one of two conditions are True and return True if only one of them is met (True and False) or (False and True).  Below is an example of this:

Sub TheIfOrFunction()

If Range("A1").Value = 100 Or Range("A1").Value = 500 Then

Range("B1").Value = Range("A1").Value

End If

End Sub

This "If" Statement will return True If Range A1 is equal to 100 OR If Range A1 is equal to 500 any other condition would return False and do nothing.

These two Operators are by far the most commonly used Operators used with the "If" Function.

So the "If" Function can be used to determine whether  a Function is either True or False and act accordingly. Combining it with the Operators "And" and "Or", can extend it's functionality.  In all the above examples the "If" Functions use the "End If" Keywords. These simply let Excel know that the "If" Function has finished. If we restrict our "If" Function to one line of code only we can omit the "End If" completely, like below:

Sub NoEndIf()

If Range("A1").Value = 100 Then Range("B1").Value = 20

End Sub

This can at times make your code slightly easier to read. There is no performance gain by doing the "If" Function this way, so don't get caught in the trap of always trying to fit your "If" Function onto one line. If by doing so you cannot read the entire line without scrolling to the right use two or more lines with the "End If".

There is one other way of evaluating a condition with the "If" and that is called the "Iif". I will only show you this because it exists, but I do not recommend using it for two reasons.

1. It's slightly slower

2. It has no advantage over the "If Else"

The syntax for IIf is:

IIf(Condition, True part, False part)

To use this in a similar way as the "If", we could use:

Sub TheIIf()

IIf Range("A1").Value = 100, Range("B1").Value = 20, Range("B1") = 50

End Sub

But as I have said I would avoid using this as it holds no advantage.

The other operator we can use with the "If" Statement is the "Not" Statement. This is used to reverse the "If" Statement

Sub IfNot()

If Not Range("A1") = 100 Then

MsgBox "Not 100", vbInformation, "OzGrid Example"

End If

End Sub

In the example above we have used the "Not" statement to reverse the logic of the "If" statement. By this I mean we have told our "If" statement to return True if Range A1 is not equal to 100