Operator Overloading Application: String Class

#include <iostream>
#include <string>
using namespace std;
int main() 
{
    // String initialization
    string str1 = "Hello"; // constructor "string(const char*)"" available
    string str2 = " World";
    // Concatenation using '+'
    string str3 = str1 + str2; // copy constructor is also available
    cout << "Concatenation: " << str3 << endl; // cout << operator is overloaded
    // String length using 'length()' function
    cout << "Length of str3: " << str3.length() << endl; 
    // Accessing individual characters using 'char operator[](int)const' operator
    // which returns a readonly character
    cout << "First character: " << str3[0] << endl;
    cout << "Last character: " << str3[str3.length() - 1] << endl;
    // Substring using 'substr()' function
    string substr = str3.substr(6, 5);
    cout << "Substring: " << substr << endl;
    // Comparison using '==' and '!=' operators
    string str4 = "Hello World";
    if (str3 == str4) 
        cout << "Strings are equal" << endl;
    else
        cout << "Strings are not equal" << endl;
    // Relational operators
    string str5 = "Apple";
    string str6 = "Banana";
    if (str5 < str6) 
        cout << str5 << " is less than " << str6 << endl;
    else 
        cout << str5 << " is greater than or equal to " << str6 << endl;
    
    // Assignment using '=' operator
    string str7 = str3;
    cout << "Copied string: " << str7 << endl;
    // Clearing the string using 'clear()' function
    str7.clear();
    cout << "Cleared string: " << str7 << endl;
    // Appending strings using '+='
    string str8 = "Hello";
    str8 += " World";
    cout << "Appended string: " << str8 << endl;
    // Finding substrings using 'find()' function
    string str9 = "Hello World";
    size_t found = str9.find("World");
    if (found != string::npos) {
        cout << "Substring found at index: " << found << endl;
    } else {
        cout << "Substring not found" << endl;
    }
    // Replacing substrings using 'replace()' function
    string str10 = "Hello World";
    str10.replace(6, 5, "Universe");
    cout << "Replaced string: " << str10 << endl;
    // Erasing characters using 'erase()' function
    string str11 = "Hello World";
    str11.erase(5, 6);
    cout << "Erased string: " << str11 << endl;
        // Converting integer to string using 'to_string'
    int num = 42;
    string strNum = to_string(num);
    cout << "Converted integer to string: " << strNum << endl;
    // Using 'getline' to read a line of text
    string input;
    cout << "Enter a line of text: ";
    getline(cin, input);
    cout << "You entered: " << input << endl;
    // Substring extraction using 'substr()' function
    string original = "Hello, World!";
    string substring = original.substr(7, 5);
    cout << "Substring: " << substring << endl;
 
    return 0;
}