Excel VBA Programming - Variables and Data Types | 2 - Variable Declarations and Assignments
Summary
TLDRThis lesson delves into the fundamentals of VBA programming with a focus on variables. It explains variables as placeholders for data, which can range from numbers to complex objects. The script covers variable declaration using the 'Dim' keyword, assigning data types, and the importance of variable names. It highlights the 'Option Explicit' setting for mandatory variable declaration and discusses variable scope, emphasizing the simplification variables bring to referencing and manipulating data within VBA code.
Takeaways
- 📌 Variables in VBA are placeholders for data, which can be a number, text, or an entire VBA object like a range, workbook, or worksheet.
- 🔑 The process of using a variable involves two main steps: declaration, where you inform VBA about the variable's name and data type, and assignment, where you give the variable a specific value.
- 💡 The 'Dim' keyword in VBA is short for 'Dimension' and is used to declare a variable, indicating the start of the variable declaration.
- 📝 Variable names in VBA should be descriptive, not exceed 255 characters, and cannot contain spaces, special characters, or be the same as VBA reserved keywords.
- 🚫 Variable names cannot start with a number or an underscore, and must be unique within the procedure they are declared in due to the concept of scope.
- ⚠️ 'Option Explicit' at the top of each module enforces that all variables must be declared before they are used, preventing potential errors.
- 🔢 Data types in VBA, such as 'Integer', define what kind of data a variable will store, which helps VBA allocate the appropriate amount of memory.
- 🔄 VBA is not case sensitive, meaning 'Age' and 'age' are considered the same variable, but it's best to maintain consistent casing for clarity.
- 🔄 Variables can simplify the process of referencing complex objects in VBA by using a simple name instead of a fully qualified reference.
- 🛠️ Variables can be used in operations just like plain numbers, making them versatile tools for manipulating data within a VBA program.
- 📈 The importance of variables will become more evident as programming progresses, especially when accessing and manipulating data on spreadsheets.
Q & A
What is a variable in the context of VBA programming?
-A variable in VBA programming is a placeholder for a piece of data, which can be a number, text, string, or a complete VBA object such as a range, workbook, or worksheet.
Why are variables important in VBA programming?
-Variables are important because they simplify the process of referencing complex objects and allow developers to avoid repeatedly writing out the same object references.
What are the two parts of a variable in VBA?
-The two parts of a variable in VBA are the declaration and the assignment of a specific value.
What does the keyword 'Dim' stand for in VBA?
-The keyword 'Dim' in VBA stands for Dimension, which is used to declare a variable and allocate a piece of computer memory for it.
What is the purpose of the 'Option Explicit' setting in the VBA editor?
-The 'Option Explicit' setting mandates that every variable must be declared before it is assigned a value, ensuring that the program explicitly states the intention to have a variable of a certain type.
What are some restrictions on variable names in VBA?
-Variable names in VBA cannot be greater than 255 characters, cannot contain spaces, mathematical symbols, punctuation characters, special characters, or be reserved VBA keywords. They also cannot start with a number or an underscore.
What is the difference between variable declaration and variable assignment in VBA?
-Variable declaration in VBA is the process of telling the program that a certain variable of a specific type will be used, while variable assignment is the process of giving that variable an actual value.
What is the scope of a variable in VBA?
-The scope of a variable in VBA refers to the boundary within which a variable exists. A variable only exists as long as the procedure in which it is declared is running.
Is VBA case sensitive when it comes to variable names?
-No, VBA is not case sensitive. A variable with a capital letter and the same variable with a lowercase letter are considered the same in VBA.
How can you use a variable in VBA after it has been declared and assigned a value?
-After a variable has been declared and assigned a value, you can reference it anywhere in the procedure's code, and it will represent the assigned value. You can also perform operations with it as you would with a plain number.
Why should variable names be descriptive in VBA?
-Variable names should be descriptive to clearly indicate what the variable represents or holds, making the code more readable and easier to understand.
Outlines
📘 Understanding Variables in VBA
This paragraph introduces the concept of variables in VBA programming, emphasizing their role as placeholders for data. Variables can hold various types of data, including numbers, text, strings, and VBA objects like ranges or workbooks. The paragraph explains the benefits of using variables, such as simplifying the process of referencing objects and avoiding repetitive object references. It also outlines the two-part process of variable creation: declaration, where memory is allocated and the variable type is specified, and assignment, where a specific value is given to the variable. The importance of choosing descriptive variable names and adhering to VBA's naming conventions is highlighted, including restrictions like no spaces, special characters, or reserved keywords, and the case insensitivity of VBA variables.
📌 Variable Declaration and Assignment in VBA
The second paragraph delves deeper into the process of declaring and assigning values to variables in VBA. It explains the 'Dim' keyword, which is used to declare a variable and must precede the variable name. The paragraph also discusses the 'As' keyword, which specifies the data type of the variable, and the importance of declaring the variable type to ensure proper memory allocation. The concept of 'Option Explicit' is introduced, which requires all variables to be declared before they are used. The paragraph further explains the rules for variable naming, including the uniqueness within a procedure, the scope of variables, and the restrictions on starting variable names with numbers or underscores. It concludes with an example of assigning a value to a variable and demonstrates how variables can be used in operations and referenced in code, highlighting the flexibility and utility of variables in VBA programming.
Mindmap
Keywords
💡Variable
💡Data
💡Declaration
💡Assignment
💡Integer
💡Scope
💡Option Explicit
💡Memory Allocation
💡Procedure
💡Case Sensitivity
Highlights
Variables are essential in VBA programming as placeholders for data.
Data can be a number, text, string, or a complete VBA object like a range or a workbook.
A variable name points to a specific object, simplifying object references.
The process of declaring a variable involves allocation of memory and specifying the data type.
The 'Dim' keyword is used for declaring variables in VBA.
Variable names should be descriptive and follow specific naming conventions.
Variable names cannot contain spaces, special characters, or be reserved VBA keywords.
The 'Option Explicit' setting requires all variables to be declared before use.
Variable scope is limited to the procedure in which it is defined.
Variable names must start with a letter and cannot start with a number or underscore.
Assigning a value to a variable involves using an equal sign and the desired value.
Variables can be used in operations just like plain numbers.
VBA is not case sensitive, and variable names with different casing are treated as the same.
Variables simplify the process of referencing complex objects in VBA.
Understanding variables is a foundational concept before diving into more advanced programming in VBA.
The lesson covers the importance and basics of variables, setting a foundation for further VBA programming.
Transcripts
in this lesson we'll talk about variables which are a very important part of VBA programming
a variable is just a placeholder for a piece of data in our program now what do I mean by a piece
of data well data can mean anything from a number to a piece of text or a string to a complete VBA
object like a range or a workbook or a worksheet a variable is just a name that we choose as a
developer that points to a specific object in our program so we don't have to reference that object
over and over and over again so if you think back a while ago when we talked about fully qualified
references for example when we used application and then workbooks and worksheets to reference
a specific range object that process of writing out that reference can take a while to write out
it's much easier to just write it out once and assign that final object reference to a variable
which again is just a placeholder name and then reference that variable instead of writing out
the entire object reference again so variables are just simple simple ways that we can refer
to something in our program without having to remember exactly what a specific value is
or a specific object is so let me go ahead and create a sample variable here for you there's
actually two parts to a variable the first is the Declaration and the second is the assignment of
a specific value so the Declaration which is the first step is the part where we tell VBA that we
want to allocate a piece of computer memory for a variable we're going to say we're going to define
a name here a specific variable which is just a name and we also have to tell VBA the kind of data
that it's going to hold so that when we assign a value to it VBA is prepared to store or reference
that specific kind of data so let me go ahead and create a brand new procedure here I'm going
to call it my first variable and as soon as I add the parentheses and press enter VBA will complete
the end sub so what I'm going to do here is write out a single variable declaration because it's a
lot to take in at first so I'm going to write it out completely and then go through it step by step
so here we go dim age as integer as soon as I do a line break perfect there it is the first part
here is the dim keyword which is actually part of VBA it's a keyword within the language dim
is short for Dimension and that's an old school computer science term for variable so dim always
has to be written before we write out any of our variables so if we had more than one variable we
always place the dim keyword before the actual name so immediately after the dim keyword we write
the name of the variable this is our own decision this is up to the developer and ideally the name
should describe what the variable is going to hold so in this case I want a variable that's going to
store my age let's say I don't want to remember it and I just want to store it in a variable once
so that I can always reference age later in the program and know that it's always going to give
me the actual numeric value of my age so age is up to me to decide in terms of the variable name
I've chosen age that's the second thing I put in this sequence of four items immediately after the
variable name I put the keyword as that also is part of VBA and that also also must always be
included and finally at the very end that's where we declare the variable type this means the type
of data that is being stored we we have as I mentioned many different types of data we have
integers we have strings we have complete DBA objects we have to tell VBA in order for it to
allocate memory exactly what we plan to store in this variable in this case age is going to be an
integer as a basic mathematic review an integer is just a number without a floating Point component
so a number without a decimal a whole number like 5 or 10 or 15. earlier on when we were looking at
some of the configuration settings in the Visual Basic editor we enabled an option that mandates
that option explicit appears at the very top of each of our modules this option explicit
setting mandates that every variable be declared before we actually assign it a value and when we
when we say variable declaration that's this part we are declaring we are telling the program as a
statement of fact that we are going to have some kind of variable called age in this procedure and
that we expect age to be of an integer type a whole number but we haven't actually assigned
it a value yet we don't know what age is equal to we just tell VBA to spare some memory for it
now there are a couple restrictions that VBA places on our variable names that I want you
to be aware of the first is that variable names cannot be greater than 255 characters you're
generally not going to run into this problem with your variable names but I did want you to be aware
of it variable names exactly like procedure names cannot contain spaces so if you have multiple
words you can stick with the upper camel case syntax which means the first letter of every word
can be capitalized and you can use that to sort of Mark where a new word begins but you cannot have
actual spaces in your variable names variable names also cannot contain mathematical symbols
like plus or minus they cannot contain any kind of punctuation characters like the question mark
or the exclamation point they cannot contain special characters like the hashtag and they
cannot be reserved VBA keywords like sub or end or option or explicit or worksheet so don't create a
variable called worksheet the variable access has to be some kind of name that isn't part of the VBA
language the variable must also be unique in the procedure that defines it which means we can't
declare another variable called age in the exact same my first variable procedure so that's going
to trigger an error in VBA however we can have the same variable names across different procedures
so if I had another procedure below my second variable and I declared a variable called age
in there that's totally valid and age in my second procedure can be a totally different data type the
reason we can do this across different procedures is because the variable has this concept of scope
and scope refers to the Limit or the reach or the boundary in which a variable exists and a
variable only exists as long as the procedure is running so every time my first variable is
executed it's going to create a variable called age that's going to be an integer but as soon as
that procedure is done that variable is tossed out of memory it doesn't exist any longer so
whenever we run a second procedure that also has a variable called age that second variable is simply
going to be created from scratch and that process continues over and over and over again finally we
cannot start a variable name with a number or an underscore the variable name can contain a
number or an underscore but it cannot start with it so the general best practice to follow is to
start your variables with a letter and just make it as descriptive as possible it should describe
the actual value that it's holding so age is a is a pretty good variable name you don't want
something like num or num1 you don't just want to say it's a number you want to describe what
it actually is what it actually represents so now that we've declared the age variable as
a type of integer we can actually go ahead and assign it a value the way we do that is on the
line below we write the name of the variable this is age this is our own custom name we're given an
equal sign much like if we were assigning a value to a property of an object just an equal sign and
then on the right side we write the actual value that we want to assign to this variable so let's
make the age variable equal to 26. so what does this mean well age is now a placeholder and it's
a placeholder for a number of 26. that means that I can reference the variable age anywhere in this
procedures code and it will give me the value 26. it's a representative of that value it's a
placeholder over it so for example if I wanted to debug print rather than writing 26 I can simply
write age and whenever VBA evaluates this it's not going to print the literal string age rather it's
going to say hey you have a variable here what does that equal to oh right here it's defined
to be 26 so I know that it's a reference to that number so this is going to evaluate to
26. so when I execute this procedure 26 is going to print in my immediate window remember that age
is a variable that represents a number but we're not limited to Simply outputting that variable we
can do any kind of operations that we would do with a plain number so for example if I wanted
message box and I want to see what my age will be in uh four years what I can do is age plus four
the reason I can do this is because age is just a name for a number it represents it's a placeholder
for the value that I assign up here so when VBA is evaluating this it's going to substitute age for
the value to sign up here 26 it's going to add 4 to get 30 and once it evaluates to 30 that's what
message box is going to output for us so when I execute this a message box with 30 is going to
appear in the middle right here One Last Detail VBA is not case sensitive which means a variable
with a capital A and a variable with a lowercase a are the exact same thing VBA will generally try
to correct you whenever you use the wrong case so for example if I try doing something like this if
I try typing age with a lowercase a you can see it's automatically going to boost it back up to
an uppercase a because it identifies that that variable exists but VBA is not case sensitive
so in case of any kind of error do not declare variables with the same name but different casing
VBA will try to correct for it but you should avoid it as a general practice if you want another
variable find a completely different name to give it that's all there is to cover in this lesson
variables are just placeholders or names that we assign to pieces of data in our code right now
I'm sure you're not seeing the the big benefit of this but rest assured variables are really helpful
when we get to the nitty gritty of actually accessing values on our spreadsheet manipulating
them overwriting them variables help simplify the process of referencing complex objects
that's all there is to cover here and throughout this entire section we're going to be diving a
lot into variables and the various data types that we can use in our code it's an important
foundation to lay before we start diving into the actual parts of programming in VBA itself
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