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| Variables and Data Types C++ Beginners Course |
2.1 Understanding Variables
- Definition: A variable is a storage location identified by a name (an identifier) used to store data.
- Declaration and Initialization:
- Declaration is when you specify the type and the name of the variable.
- Initialization is when you assign a value to the variable.
```cpp
int age; // Declaration
age = 25; // Initialization
int year = 2024; // Declaration and Initialization
```
2.2 Data Types in C++
- Primitive Data Types:
- int: Integer numbers.
- float: Floating-point numbers.
- double: Double precision floating-point numbers.
- char: Single characters.
- bool: Boolean values (true or false).
- Examples:
```cpp
int num = 10;
float temperature = 36.6;
double preciseValue = 3.14159;
char grade = 'A';
bool isPassed = true;
```
2.3 Type Modifiers
- Modifiers: Used to alter the size and/or range of the data types.
- signed, unsigned: For integer types to define whether they can store negative values.
- short, long: To alter the size of integer types.
- Examples:
```cpp
unsigned int positiveNumber = 100;
long int largeNumber = 1000000;
```
2.4 Constants
- Definition: Constants are fixed values that do not change during the execution of a program.
- Using `const` Keyword:
```cpp
const int MAX_AGE = 100;
```
2.5 Basic Input/Output with Variables
- Input Example:
```cpp
int number;
cout << "Enter a number: ";
cin >> number;
cout << "You entered: " << number << endl;
```
2.6 Understanding Scope
- Local Variables: Declared inside a function or a block and can only be used within that scope.
- Global Variables: Declared outside all functions and can be accessed from any function within the same file.
- Example:
```cpp
int globalVar = 10; // Global variable
int main() {
int localVar = 5; // Local variable
cout << "Local variable: " << localVar << endl;
cout << "Global variable: " << globalVar << endl;
return 0;
}
```
2.7 Type Casting
- Implicit Casting: Automatic conversion by the compiler.
- Explicit Casting: Manual conversion using cast operators.
```cpp
int i = 10;
double d = 5.5;
// Implicit casting
double result = i + d; // i is automatically converted to double
// Explicit casting
int truncated = (int)d; // d is explicitly converted to int, truncating the decimal part
```
2.8 Summary
- Recap of variables, data types, type modifiers, constants, and type casting.
- Importance of understanding variable scope and proper use of types.
2.9 Exercises
- Exercise 1: Declare variables of different types and print their values.
- Exercise 2: Write a program that takes two integers from the user and prints their sum, difference, product, and quotient.
- Exercise 3: Create a program that uses both local and global variables and demonstrates their scope.
This chapter introduces the fundamental concepts of variables and data types, providing a solid base for understanding how to store and manipulate data in C++. The exercises will help reinforce these concepts through practical application.