C++ Variable

The C++ variable is a named storage location in memory used to store data that can be accessed and manipulated by your program. Variables have a data type that defines the type of data they can hold, such as integers, floating-point numbers, characters, and more. Here’s how you declare and use variables in C++:

Variable Declaration:

To declare a variable, you specify its data type followed by the variable name:

data_type variable_name;

For example:

int age;            // Declares an integer variable named 'age'.
double salary;      // Declares a double-precision floating-point variable named 'salary'.
char grade;         // Declares a character variable named 'grade'.

Variable Initialization:

You can also initialize a variable at the time of declaration by assigning it an initial value:

data_type variable_name = initial_value;

For example:

int age = 30;           // Initializes 'age' to 30.
double salary = 50000;  // Initializes 'salary' to 50000.0.
char grade = 'A';       // Initializes 'grade' to the character 'A'.

Variable Assignment:

After declaring and initializing a variable, you can assign new values to it during the execution of your program:

variable_name = new_value;

For example:

age = 35;          // Assigns a new value (35) to 'age'.
salary = 55000.5;  // Assigns a new value (55000.5) to 'salary'.
grade = 'B';       // Assigns a new value ('B') to 'grade'.

Using Variables:

You can use variables in expressions, assignments, and other operations within your program. For example:

int x = 5;
int y = 10;
int sum = x + y; // Adds the values of 'x' and 'y' and stores the result in 'sum'.

Variable Names:

Variable names must adhere to certain rules and conventions:

• Variable names are case-sensitive (e.g., myVar and myvar are different).
• Variable names must start with a letter or underscore (_), followed by letters, digits, or underscores.
• Variable names should be meaningful and describe the purpose of the variable (e.g., counter instead of c).

Here’s an example that demonstrates declaring, initializing, and using variables in C++:

#include <iostream>

int main() {
    int age = 30;
    double salary = 50000.0;
    char grade = 'A';

    std::cout << "Age: " << age << std::endl;
    std::cout << "Salary: $" << salary << std::endl;
    std::cout << "Grade: " << grade << std::endl;

    return 0;
}

This program declares and initializes variables for age, salary, and grade, and then prints their values to the console.