What are variables?

Variables are data values that software developers use when values can change during the course of a computer program. You are certainly familiar with variables from mathematics; the basic variable concept is identical to the use of variables in programming. Programming has added a few more properties to the variable concept, which we will explain here.

You should remember this as a variable:

The main difference between a variable and a constant is that the value associated with a variable name can change during program execution.

What are program variables for?

Variables are indispensable tools in programming. Program variables are used as abstract concepts at different levels of abstraction in computer programs. One such variable concept is the notion of variable plans, which represent stereotypical uses of variables. A frequently used concept is the conditional expression.

How do variables work?

Variables are always used by programmers to store information that is referenced in a computer program. The value of a variable can be manipulated using a function or an instruction. The program variables naturally also offer the option of assigning a descriptive name to data via the variable name. With the individual variable name, our programs are easier to understand for the programmer and any other reader. It is helpful to think of variables as containers for information. Their sole purpose is to identify and store data in memory. This data can then be used throughout the program. This has the advantage that the variable values can be accessed and worked with at any time.

Assignment of values to variables

Naming variables is one of the most difficult tasks in computer programming. When naming a variable, you should think carefully about the variable name. Do your best to make sure that the name you assign to your variable accurately describes and is easily understood by others. Very often you are the one in the role of program reader when you look at a program you wrote several months or even years ago… When you assign something to a variable, you use the equal sign “=” as a symbol. On the left side is always the name of the variable, on the right side the value you want to store in the variable.

vorname = 'Sascha'

Here we have assigned the value “Sascha” to the variable firstname, this value is a string. Therefore, this variable assignment is only valid if we have previously defined this variable as a string. Some programming languages also use variable variable value concepts, but such dynamic reference variables also have their pitfalls…

Variable properties:

  • Variables can change during program execution.
  • the variable is the most frequently used tool in programming
  • a variable has a variable name assigned by the programmer
  • Variable concepts exist in every programming language
  • Variables can have different properties from programming language to programming language

Although variables have slightly different properties from programming language to programming language, the basic concepts are always very similar.

Examples of the use of variables in a program

If a program is to accept input from a user, then the variable is the classic concept for recording these values and storing them in a data type. If you want to ask the user a question in a program, the variable can record the answer.

Everything you need to know about variables in programming

Variables are the foundation of every computer program. They allow data to be flexibly stored, manipulated and shared between different parts of the program.

Why variables are so important

Whether you are just starting out with programming or implementing a complex project, understanding variables and their properties is essential for clean, effective code.

The meaning of data types

Variables have a close relationship to data types in every programming language. A data type defines what kind of values a variable can store and which operations can be applied to these values. The most common data types are

  • Integer (whole numbers): Numbers without decimal places such as 42 or -7.
  • Float (floating point numbers): Numbers with decimal places such as 3.14 or -0.001.
  • String (character strings): Texts such as "Hallo Welt"
  • Boolean (truth values): Values such as true or false.

Choosing the right data type for a variable is crucial to ensure that your program works efficiently and correctly.

Variable scope (scope of validity of variables)

The scope of a variable indicates where in the program it can be accessed:

  • Global variables: These variables are available throughout the entire program. They are declared outside of functions.
  • Local variables: These variables are only available within the function or block in which they were declared.
  • Block scope: Some programming languages such as JavaScript support variables with block validity (e.g. with let or const), which are only accessible within a specific code block.

Understanding scopes helps you to avoid collisions of variable names and to make the code clearer.

Best practices for naming variables

Good naming of variables is essential to keep the code understandable and maintainable. Note the following tips:

  • Choose descriptive names: Instead of x or y, you should use descriptive names such as benutzerName or artikelPreis.
  • Avoid abbreviations: Abbreviations such as usrNm or prc can make the code incomprehensible.
  • Follow conventions: Many languages have certain naming standards, such as CamelCase (benutzerName) or Snake_Case (benutzer_name).
  • Avoid overloaded names: Do not use names that are already defined as keywords in the programming language (e.g. int, for or class).

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