Variables and constants

What are Variables?

Variables are fundamental components in programming languages like C++. They act as containers to store data values that can change during the execution of a program. Think of them as named placeholders for storing information in the computer's memory.

Declaration and Initialization:

• Declaration: To create a variable, you declare its type and name. This informs the compiler about the type of data the variable will hold and reserves memory space accordingly.

Initialization: After declaring a variable, you can initialize it by assigning a value. Initialization sets the initial value of the variable.

Variable Naming Rules:

• Variable names must begin with a letter (uppercase or lowercase) or an underscore (_).
• Subsequent characters can be letters, digits, or underscores.
• Variable names are case-sensitive (age, Age, and AGE are different).
• Avoid using reserved keywords (words with special meaning in C++) as variable names.

Variable Types:

• Data Types: Variables have types that determine what kind of data they can store. For example, int, float, char, bool, etc.
• Size and Memory: Each variable type occupies a specific amount of memory in the computer's memory, and its size depends on the data type.

Using Variables:

• Assignment: You can change the value stored in a variable by assigning a new value to it.

Usage: Variables can be used in expressions and statements throughout the program.

Scope of Variables:

• Scope: Variables have a scope, which defines where in the program they are accessible. Variables declared within a block of code are typically only accessible within that block (local scope), while variables declared outside of any function or block are accessible throughout the program (global scope).