Hi there, I'm going to kind of explain how to declare variables and I'm going to talk about data types, and the scope of variables in this screen cast. So, sure a lot of you have wondered what it means to have dim statements. So first example, we have a dim statement here, we're dimming all these different things as doubles. So I'm going to kind of talk about what those are. All variables, if you have the Option Explicit, need to be declared that's what Dim means. Dim is for dimensionalize, you basically set aside space for it. So the most common type of data in VBA is a double. That's used for numbers with decimal fractions, and high precision exponents extended range. This is essentially, you can think of a double as a real number. The precision is 15 to 16 significant figures. Integer is another common data type, strings are also quite common. We're going to have a whole module just working with strings. Single used to be one of the most common types before, because it uses only half the memory as doubles. Long, which goes from -2 billion to 2 billion they're integers. Booleans are a data type which is true or false. If you don't dim the default is variant, and it's sort of just accordingly. So it sort of detects what it is, and then another common one would be range. You can also dim things as currency, as dates, as there's all sorts of data types. Let's talk real quick about the scope of a variable and that is how far is the reach of the variable and where it can be seen. So, you can make it so it's only within a single procedure. So, it's local to either a sub or a function. This is declared using a Dim or Static statement within the procedure, or it can be within the current module. So you can dim something and you can declare a variable and it will be available throughout the entire module. So I've got an example on that. You can also use the Public statement to Dim it in all procedures and all modules open in the current workbook. So just kind of an example, we might have a workbook this blue square rectangle we might have two modules. If you dim k outside of the module, then that means k here is going to be available to both Sub One and this Funky function. Y here is only going to be available to the Funky function, it's not going to be able to be seen anywhere else. We've got this public R, if you make it public then this is going to be available to anything in the workbook, not just in module 2. So we could Reference that, we wouldn't have to re-dim it in any of these modules. J here is only in Sub Two, and when you're making functions, so the argument of the function it's just local to that function. So let's work through an example, I've got a sub here. We just calculate pi 4 times the arctangent of 1, we get the radius of a sphere. In an input box, we calculate the surface area. We output that in a message box, and then I subcontract out the work of calculating the volume to this SphereVolume function. So let's go ahead and step through this using F8, we obtain this in an input box, we calculate the area, we message box that. The surface area is 314, and now we go into the function. But you notice that we have a problem here because pi hasn't been declared within the sphere volume function. So to bypass that, you could dim pi as a double. We also need to define what pi is separately in this function. So now when we do this, when me run the sphere. Enter the radius of 5, it displays the area, and it also displays the volume. However, if we wanted to we can dim pi outside at the modular level, so I'm going to eliminate this. I'm going to delete pi here, and the pi here, I'm going to dim outside of the procedures. So this is at the modular level. You notice I'm using pi here and assuming we define it in a kind of step wise fashion when we jump into the function here it's already going to have the value of pi because pi is at the modular level. And so let's go ahead and run this, we get 5 and we get the surface area, and also the volume. So we don't have that error that we did when we dimmed pi inside the module. So what if this function were in a different module, so in Module 2. If that's the case, it's not going to work because dimming pi outside of the procedure here, this is only going to be available to all procedures in Module1. So to bypass this, we can use the public statement. So now, pi is going to be available to everything in the workbook. So any module in this workbook, including Module2, in which we have pi. So if you can see, when we step through this, that it goes in to the function on Module2, but we still have the value of pi. And we message box that, and that's exactly what we got earlier. So if you're working with procedures that are in different modules and you want to be able to pass the value without re-dimming, then this is how you can do it. And it's tremendously useful if you know what you're doing. All right, real quick I wanted to explain what this static statement is. So here I just have a non-static example. This sub I'm dimming d as an integer and I'm just saying d = d + 1 and I message box that. So let me show you what that does, we run the non-static and so I run it, it gives us a message box of 1. We run it, it's 1, I run again, it's 1. All right, so it basically resets the variable every time you run it. However, if you static, if you instead of dim, you can write Static d As Integer. It’s exactly the same as the sub up here, but let me show you what happens. So that’s this run static, we run it once and it displays 1, run it again, it’s 2. So it always keeps the value and we’re adding 1 every time. If you close the file and reopen it, it’s set to a zero, but this is how you can remember the value of a parameter. So here's kind of a cool example of some more complex things we can do with this static variable. This sub is the same as it was, I've added this optional reset as Boolean. And I have another line here, if reset, if that's true, then d = 0. So there's this optional argument to a sub, and it's a Boolean. So if reset is true, then we're going to reset d to 0, all right? So this is how we can reset a static variable back to 0, and we have to run the reset from another subroutine. So all this does is it runs the static example and passes the argument of true through here. So when we run this sub, it's going to pass true, it's going to then reset d to 0. So let's go ahead and show you what happens and we're still running the static. 1, 2, 3, 4, 5, and so on and now when I do reset, it resets d to 0, but the the first line is the incremented it by 1 and we get the message box. So I hope you learned a lot about declaration of variables, data types, and the scope of variables. Thanks for watching.
