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In this video, we're going to be talking about array's and how we might use them in visual basic.

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And so this begs the question, what is an array?

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An array is a specific type of variable in VBA that can store multiple values instead of a single value.

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So whereas a normal variable in VBA can only store one value at a time, your array type variable can

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store an entire list of values so long as they are the same data type.

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So for example, if we had a list of student names John James, Hannah, Connor and Christina, we would

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have to create five separate variables if we wanted to store each of those values in its own normal

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VBA variable.

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If we created an array variable, on the other hand, we could store all five of those names at once

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and only require one variable declaration.

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So this kind of begs the question, how do arrays work?

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So arrays are going to first take your list of values that you're giving.

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Turn them into a little less like it's shown on the right and then turn each of those items into an

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individual item itself.

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So instead of having five separate variables, storing five separate values, we can set up an array

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ahead of time to expect five values.

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It will create five separate little item boxes.

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And then as we assign those item boxes values, each of those items gets assigned its own number.

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So in this case, that array on the bottom has green boxes for John, James, Hannah, Connor and Christina.

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All five of those names get their own box, their own value, but they all exist within the same array.

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They're separated by a numbering system, an indexing system that starts with zero.

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And I might not seem intuitive at first, but starting with zero for indexing is pretty standard for

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all programming languages.

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So instead of counting from one and going up to five four lists of names, the system will start from

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zero and go up to four.

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And we'll see examples of this when we actually talk about using arrays in visual basic.

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You can see here that we have a single array.

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It's a single variable, but we're storing all five items separately within our array.

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And that's why we like to use arrays, arrays can significantly simplify the code.

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Because you can reduce the number of variables that you have to set up a number of variables that you

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have to actually go in and store values to and retrieve.

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Values from arrays are also a lot more flexible than a regular variable type.

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They can continue to grow if we have a longer list.

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We can continue to add items onto that list.

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They can shrink if we need to shrink them.

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Later on.

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We realized we didn't have as many values as we thought.

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So in this table on the left, this green table, we can see if we were to use standard variable naming

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system, we'd have to create five variables.

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Student one, student to student three, student four and student five.

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We do then have to assign each one of those variables of value.

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And later in our code, we'd have to remember which variable meant which name and know which variable

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to be referencing at whatever time we need in our code.

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If we did this with an array, however, we could create one array variable.

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In this case, it would be students and then each of those items in the array could get assigned a value.

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So what's one variable declaration compared to the five variable declarations that we would need on

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the left?

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And this leads into the difference between static and dynamic arrays.

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So static arrays have a preset size.

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That means they can only take a certain number of items.

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And we'll tell the system ahead of time.

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Hey, this array that we're about to build for you, it's only going to have four items in it.

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All you only ever need to expect four items.

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So static arrays are good for when, you know, ahead of time exactly how many items you're going to

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have in that array.

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But if you had a list and you weren't sure how long your list was and you weren't sure if your list

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was actually going to grow or if it might shrink later on, you could use a dynamic array.

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And the dynamic Rakan is exactly as it sounds.

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Grow and shrink as you add things or take things out.

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So in the previous examples, we had exactly five names.

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We knew how many names there were going to be.

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So we could declare our array as a static array.

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Meaning when we declared the array, we tell the system ahead of time recreating an array variable called

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students.

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And it's going to have zero to four, meaning zero one, two, three and four, all as items within

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this array.

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And it's going to be a string type variable.

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That would be a static array.

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This system knows ahead of time.

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All right.

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I should have index numbers from zero to four.

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And that's the only size that this array should ever be.

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But if we were worried, for example, that we might have more students in the future or that some of

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our existing students, by graduate, we could set up that array to be dynamic, meaning can grow and

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shrink depending on however many values we feed that array.

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And in this case, when we create the array, we just don't give it a size.

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We let the system determine the size as we go.

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So in this video, we talked about VBA arrays.

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We talked about how they work, why we would use them.

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The difference between static and dynamic arrays.

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And now we're ready to go ahead and take a look at how to use arrays in visual basic.