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Chapter 2

Elementary Data Types

Master scalar and composite data types, understand memory management, and learn type properties in C++.

2.1 Properties of Types and Objects

Understanding the fundamental properties that define types and objects in C++.

Aspect Definition Example
Static Types Fixed during compile time. int x = 369;
Dynamic Types Determined at runtime. var x = 369; (in dynamic languages)
Mutability Whether an object can be modified. const int x = 369;
Address Memory location of an object. &x gives the address of x
Lifetime Duration during which an object exists. Local variables exist during function execution
▶ Type Properties Example 
#include <iostream>
using namespace std;

int main() {
    // Static typing - type known at compile time
    int x = 369;
    const int y = 100;  // Immutable
    
    cout << "Value of x: " << x << endl;
    cout << "Address of x: " << &x << endl;
    
    // y = 200; // Error: cannot modify const
    
    // Lifetime demonstration
    {
        int temp = 50;  // temp exists only in this block
        cout << "Temp value: " << temp << endl;
    }
    // temp is destroyed here
    
    return 0;
}
Click "Run Code" to execute

2.2 Scalar Data Types

Basic data types that hold single values.

Aspect Definition Example
Integer Whole numbers. int x = 369;
Floating Point Decimal numbers. float y = 3.69;
Character Single character. char ch = 'A';
Boolean Represents true/false values. bool isTrue = true;
Size and Range Depends on the system architecture. int: -2^31 to 2^31-1

📊 Data Type Sizes Comparison

▶ Scalar Data Types Example 
#include <iostream>
using namespace std;

int main() {
    // Integer types
    int age = 25;
    short year = 2024;
    long population = 8000000000L;
    
    // Floating point types
    float pi = 3.14159f;
    double precise = 3.14159265359;
    
    // Character type
    char grade = 'A';
    
    // Boolean type
    bool isPassed = true;
    
    // Display values
    cout << "Age: " << age << endl;
    cout << "Pi (float): " << pi << endl;
    cout << "Pi (double): " << precise << endl;
    cout << "Grade: " << grade << endl;
    cout << "Passed: " << isPassed << endl;
    
    // Size of data types
    cout << endl << "Sizes:" << endl;
    cout << "sizeof(int): " << sizeof(int) << " bytes" << endl;
    cout << "sizeof(float): " << sizeof(float) << " bytes" << endl;
    cout << "sizeof(double): " << sizeof(double) << " bytes" << endl;
    cout << "sizeof(char): " << sizeof(char) << " byte" << endl;
    
    return 0;
}
Click "Run Code" to execute

2.3 Composite Data Types

Complex data types that combine multiple values.

Aspect Definition Example
Arrays Collection of elements of the same type. int arr[3] = {3, 6, 9};
Structures Groups related variables of different types. struct Tesla { int id; char name[10]; };
Classes User-defined data types with methods. class MyClass { public: int x; };
Pointers Holds memory address of another variable. int* ptr = &x;
Enums Represents named integral constants. enum Day { MON, TUE, WED };
▶ Arrays Example 
#include <iostream>
using namespace std;

int main() {
    // Array declaration and initialization
    int numbers[5] = {3, 6, 9, 12, 15};
    
    cout << "Array elements:" << endl;
    for(int i = 0; i < 5; i++) {
        cout << "numbers[" << i << "] = " << numbers[i] << endl;
    }
    
    // Multi-dimensional array
    int matrix[2][3] = {
        {1, 2, 3},
        {4, 5, 6}
    };
    
    cout << endl << "Matrix:" << endl;
    for(int i = 0; i < 2; i++) {
        for(int j = 0; j < 3; j++) {
            cout << matrix[i][j] << " ";
        }
        cout << endl;
    }
    
    return 0;
}
Click "Run Code" to execute
▶ Structures Example 
#include <iostream>
#include <cstring>
using namespace std;

// Structure definition
struct Tesla {
    int modelNumber;
    char name[20];
    float batteryCapacity;
    bool autopilot;
};

int main() {
    // Create and initialize structure
    Tesla model3;
    model3.modelNumber = 3;
    strcpy(model3.name, "Model 3");
    model3.batteryCapacity = 75.0;
    model3.autopilot = true;
    
    // Display structure data
    cout << "Tesla Information:" << endl;
    cout << "Model Number: " << model3.modelNumber << endl;
    cout << "Name: " << model3.name << endl;
    cout << "Battery: " << model3.batteryCapacity << " kWh" << endl;
    cout << "Autopilot: " << (model3.autopilot ? "Yes" : "No") << endl;
    
    return 0;
}
Click "Run Code" to execute
▶ Pointers Example 
#include <iostream>
using namespace std;

int main() {
    int num = 369;
    int* ptr = &num;  // Pointer to num
    
    cout << "Value of num: " << num << endl;
    cout << "Address of num: " << &num << endl;
    cout << "Value of ptr: " << ptr << endl;
    cout << "Value pointed by ptr: " << *ptr << endl;
    
    // Modify through pointer
    *ptr = 500;
    cout << endl << "After modification through pointer:" << endl;
    cout << "Value of num: " << num << endl;
    
    // Pointer arithmetic
    int arr[3] = {10, 20, 30};
    int* arrPtr = arr;
    
    cout << endl << "Pointer arithmetic:" << endl;
    for(int i = 0; i < 3; i++) {
        cout << "arr[" << i << "] = " << *(arrPtr + i) << endl;
    }
    
    return 0;
}
Click "Run Code" to execute

🎯 Pointer Memory Visualization

▶ Enumerations Example 
#include <iostream>
using namespace std;

// Enum definition
enum Day {
    MONDAY = 1,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY,
    SATURDAY,
    SUNDAY
};

enum TeslaModel {
    MODEL_S,
    MODEL_3,
    MODEL_X,
    MODEL_Y
};

int main() {
    Day today = WEDNESDAY;
    TeslaModel myTesla = MODEL_3;
    
    cout << "Today is day: " << today << endl;
    cout << "My Tesla model: " << myTesla << endl;
    
    // Using enum in switch
    switch(myTesla) {
        case MODEL_S:
            cout << "You have a Model S - Luxury sedan" << endl;
            break;
        case MODEL_3:
            cout << "You have a Model 3 - Affordable sedan" << endl;
            break;
        case MODEL_X:
            cout << "You have a Model X - SUV" << endl;
            break;
        case MODEL_Y:
            cout << "You have a Model Y - Compact SUV" << endl;
            break;
    }
    
    return 0;
}
Click "Run Code" to execute

💡 Practice Exercise

Try these exercises to master data types:

  • Create an array of your favorite numbers and calculate their average
  • Define a structure for a Student with name, age, and grade
  • Use pointers to swap two integer values
  • Create an enum for months of the year
  • Experiment with different data type sizes using sizeof()
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