Before we jump to what is a programming variable, are you aware that the first computer programming language was created in 1843? Because there were no computers at the time, Ada Lovelace created the first machine algorithm, which she recorded on paper for an early computing device.
The majority of computer programming languages draw ideas from earlier languages or expand upon them. Modern computer programming languages ease the jobs of programmers while still providing a solid foundation for future ones. To meet all of their data, transaction, and customer service demands, businesses largely rely on programmers. For their studies, science and medicine need sophisticated and precise programmers. In order to satisfy user requests, mobile applications must be updated. And all of these expanding and new requirements guarantee that programming languages for computers, both old and new, will continue to play a significant role in modern life.
So, what is a programming variable?
A set of well-defined instructions given to the computer to solve a particular solution after processing the inputs is called programming. Variables basically refer to values that can be changed easily instead of permanent values. To answer the question of what is programming variable, it can be defined as “a variable is a memory cell or memory location to store the value and information that can be changed at any time in a program”.
With the storing of values and information, it also provides a facility for data labeling by giving well-defined names. These data labels provide a better understanding of the programmers or readers. These variables containing the data or values can be used anywhere in the program for one or more desired times.
A computer always stores the data by dividing its memory into small units or cells with uniquely identified individual addresses. In several terms, the answer to the question of what is a programming variable is defined as: “A variable uniquely identifies and stores a value in programming.” However, the values or information can be different data types, such as numeric values, alphabetic values, and alphanumeric values. In programming, every term has its own unique method of writing. This unique method is called “Syntax.” Syntax refers to the specified method according to the set of rules. So the syntax of a variable is defined as below:
The syntax for variable declaration in a program.
Data type Identifier(Variable_name);
Syntax for variable Intialization:
Data type Identifier(Variable_name)= Values you want to store;
Variable Declaration:
Variable deceleration means defining the variable in the program without storing any particular value. In this case, the program acknowledges the variable with a garbage value or blank value.
Variable Initialization:
Variable initialization means defining a value for a variable for use in programming when required.
Data Types:
In the field of programming, data type describes the type of value that is going to be stored in a variable. The cells of the memory are also classified according to the data types of the values coming from the different variables. Each data type requires specific storage space, such as an integer type taking 4 bytes and ‘smallint’ taking only bytes to store the value of a variable. The following table also defines the data types.
| Data type | Used for | Example |
| Integer (Int) | Whole Numbers | 1, 11, 66, 900, 78, 65, 45, 34, 7765, 8907 |
| String (str) | Alphabetic Character and whole number | (A-Z), (a-z), AbC123, Samr123, Sam0 |
| Float (float) | Decimal-Based numbers | 1.1, 22.22, 0.001, 121.0202, 00.101, 0.5 |
| Character (Char) | Individual letter | A, d, d, f, g, r, t, y, j, k, l |
| Boolean (Bool) | Binary values | 0/1 true, false |
These are the main data types used for variables, and most of the work in programming lies between these data types. Furthermore, the following table provides pure variable defining examples in programming with respect to the data types and different data types require different amounts of memory, as described in the column below.
| Data type | Variable Example | Memory Usage |
| Integer (Int) | Int Danial=100; | 2 Byte |
| String (str) | String Alex=” SAMR”; | 1 Byte Per Character |
| Float (float) | Float Danial=90.001; | 4 Byte |
| Character (Char) | Char Alex=’x’; | 1 Byte |
Identifiers:
Identifiers are the names of the variables or labels of the variables that differentiate one variable from another variable and also provide ease to the memory location to store variable values in a uniquely identified name cell. For example,
int Danial=123;
int Alex=456;
These Danial and Alex are the labels of corresponding values that are going to be stored in memory cells. Furthermore, there are specified rules for naming variables in a program. Before writing any variable name, these rules must be followed. In case of any violation, the program will generate an error and the program will not read this variable, which also blocks the programming.
Naming Rules for Variable in Programming:
- Blank spaces are not allowed in a variable’s name. These programming languages don’t allow blank spaces in the identifiers of variable names. For example (int Mr. Danial=234;) So you must write a variable name without any blank spaces.
- The first letter of a variable name should be a character, for example (int D12l=34;). Variable names must start with a letter of the alphabet and several special signs(_,$) named underscore and dollar sign are allowed as the first character in the variable name, such as (int _danial=4; ) (int $danial=4; ). These types of names are not allowed for the variable name ( int 1danial=4;). Instead of this user can write (int danial1=4; ) which is valid and acceptable.
- All programming languages are case-sensitive, which means both upper and lower case characters can be used for variable names, but upper case variable names such as ‘DANIAL’ and lower case name ‘danial’ will be considered two different variables.
- Special words and built-in keywords are not allowed for the names of variables. These keywords are also called reserved words, and every programming language has its own predefined reserved words, having a particular meaning and functionalities such as printf, if, else, do, while, and for.
- Some programming languages have a limited range for writing variable names, but a suitable range and a good programming approach limit the name of a variable to up to 31 characters long. Programming languages like C++ allow the programmer to write up to 255 characters. Sometimes variable names have more than 31 characters. The compiler automatically considers the first 31 characters as a variable name.
- Special symbols are also prohibited for writing variable names. However, they can be used with the combination of alphanumeric characters such as (int d@nial=56; ).
- Programming languages are strongly typed languages. It clearly shows that a declared variable name can’t be changed while writing a program. However, its value can be changed where required.
These naming rules of variables deploy in almost all programming languages. In every language, however, the other rules are different but in the case of variables, all the naming rules are the same as above written.
Furthermore, the Scope of the programming variable is defined which may also help to clarify the answer to the question What is the programming Variable?
Scope of Variable:
The Scope of a variable describes variable availability for use in the whole program. Initially, scope determines where the variable is initialized or declared by the programmer. Different scopes of a variable have different types of behaviors and usability. There are two types of variable scope.
- Local Variable
- Global Variable
Local Variable:
A local variable is a type of variable that is initialized within a block of code and can only be accessed within the specific block of code. Sometimes these scope-based variables are called “initialized variables” or “value-defined variables” because most of the time these variables are initialized instead of only declared. Moreover, local variables in different blocks of the program are allowed to use the same names. Data can be stored separately by using the same name of the variable in a block of the program. Local variables having the same name in different blocks will not affect the values of the other variables contained in the different blocks with the same identifiers.
The following example elaborates on the different blocks with the same identifier of the local variable.
In the above program, every block has a local variable named AMOUNT. As we can see in the main function, the value of the local variable is still 1000 and the other variable with the same name is distinct. In the TRI() function, the variable amount also has different values, as does the QUAD() function, which also contains the same identifier variable with different values without changing the value in the main function, even though both functions are also called. This functionality is also called the method definition.
The main idea in this example is to remember that the variable name is irrelevant. It is only the scope of the variable that defines the accessibility of the variable within the program. The advanced languages of programming facilitate the programmer by releasing the allocated memory of the local variable when the block of the program or the particular function has finished running. This is the main advantage of the local variables that they provide efficiency and sustainability by releasing the allocated memory.
Global Variable:
A variable that is accessible anywhere in the whole program is called the Global Variable. These variables are global as the name implies. Once a global variable is declared, a uniquely identified memory cell is allocated for the variable throughout the runtime of a program. These types of variables can be accessed by all the methods or functions within the whole program. Multiple global variables can also be included in a single program, A group of multiple global variables is called a global environment or global state. They refer to the several aspects or environments of the source code during the runtime of a program. They are mostly written just after the libraries because most programmers find difficulties in the form of several bugs due to the inappropriate global variable declaration. They are permanent variables and require particular memory allocation for storing data or values. In the context of programming, global variables are declared outside of the main function. These global variables are not initialized most of the time; they are only declared by the programmers.
A global variable may also affect the complete code because a function or a block of code in the program can change it according to the requirements.
These types of variables are usually permanent memory consumers so in the early age of programming, memory was limited, preciseness, aggregation, summarization in programming was a good approach, and usage of global variables was the bad approach in the context of memory consumption. It was also quite difficult to track the values of the global variable in the large programs and the programmer got stuck in the debugging phase because of too many lines of code with a variable that is declared global and it was also difficult to track the changing in a global variable.
Multiple programming languages in the early programming age were based on global variables such as initial stages or versions of the COBOL programming language and the BASIC programming language. These versions of the programming language were non-structured and used only global variables. The following example will elaborate on the global variable.
The above example shows the global variable named AMOUNT with the data type of integer. There are two functions named Tri() and Quad (TM). Both use the global variable because global variables can be used anywhere in the whole program in the main function before the TRI() function and QUAD() functions. AMOUNT value is the same as 1000, and after these functions, the value of the global variable is still the same as 1000. In TRI() and QUAD() functions, the value of the global variable is multiplied by the corresponding values, such as 1000 *3 and 1000*4.
Summary:
The question “what is a programming variable” is answered by showing the definition of the variable, which shows the variable in programming. After that, supporting items of variables in programming take place, such as data types and identifiers. With these items, an important phase also occurs named “Naming Rules of a variable.” This term defines how to write a suitable name for a variable. Furthermore, the main types of variables take place by showing the availability of the variables with examples.