Mastering C++: From Fundamentals to Advanced Programming

Chapter 5: Arrays, Strings, and Pointers in C++

🔹 1. Introduction

In this chapter, we’ll explore the core data manipulation tools in C++:

• Arrays: Store multiple values of the same type in one variable.
• Strings: Represent and manipulate sequences of characters.
• Pointers: Directly access memory locations.

Together, they form the foundation of low-level programming, data structures, and memory optimization in C++.

🔹 2. Arrays in C++

✅ What is an Array?

An array is a fixed-size collection of elements of the same data type, stored in contiguous memory.

✅ Declaring and Initializing Arrays:

int nums[5];                  // Declaration

int scores[3] = {90, 80, 70}; // Initialization

✅ Accessing Elements:

cout << scores[0];  // 90

✅ Looping Through Arrays:

for (int i = 0; i < 3; i++) {

    cout << scores[i] << " ";

}

🔹 3. Multidimensional Arrays

✅ Syntax:

int matrix[2][3] = {

  {1, 2, 3},

  {4, 5, 6}

};

✅ Accessing Elements:

cout << matrix[1][2]; // 6

✅ Nested Loop Example:

for (int i = 0; i < 2; i++) {

    for (int j = 0; j < 3; j++) {

        cout << matrix[i][j] << " ";

    }

    cout << endl;

}

🔹 4. Strings in C++

C++ supports both:

• C-style strings (character arrays)
• std::string class (from the Standard Library)

✅ C-style String:

char name[6] = "Alice";

cout << name;

✅ Common String Functions (C-style):

#include <cstring>

strlen(name);          // Length

strcpy(dest, src);     // Copy

strcmp(a, b);          // Compare

✅ Using std::string:

#include <string>

string name = "Bob";

cout << name.length();  // 3

✅ String Functions (std::string):

name.append(" Smith");

name.substr(0, 3);      // Substring

name.find("o");         // Index of 'o'

✅ std::string is easier and safer to use than char arrays.

🔹 5. Introduction to Pointers

✅ What is a Pointer?

A pointer stores the memory address of a variable.

✅ Declaring and Using Pointers:

int x = 10;

int *ptr = &x;

cout << *ptr;   // 10 (value)

cout << ptr;    // address

✅ Pointer Arithmetic:

ptr++; // Moves to the next memory location

✅ Use * to dereference (access value), & to get address.

🔹 6. Pointers and Arrays

int arr[] = {1, 2, 3};

int *p = arr;

cout << *p;     // 1

cout << *(p+1); // 2

Arrays and pointers are tightly related — the array name acts as a pointer to the first element.

🔹 7. Pointers with Functions

void update(int *n) {

    *n += 5;

}

int main() {

    int a = 10;

    update(&a);

    cout << a;  // 15

}

✅ Pointers allow functions to modify arguments directly.

🔹 8. Summary Table