strings.cpp

#include <iostream>
#include <string>  // Standard library for string operations
using namespace std;

int main() {
    // ==========================================
    // 1. STRING CONCATENATION (Combining Text)
    // ==========================================
    cout << "=== 1. STRING CONCATENATION ===" << endl;
    string firstName = "John";
    string lastName = "Doe";

    // Method A: Using + operator (add " " for space)
    string fullName1 = firstName + " " + lastName; 
    cout << "Using + operator : " << fullName1 << endl;

    // Method B: Using append()
    string fullName2 = "John ";
    fullName2.append("Doe");
    cout << "Using append()   : " << fullName2 << endl;


    // ==========================================
    // 2. NUMBERS VS STRINGS
    // ==========================================
    cout << "\n=== 2. NUMBERS VS STRINGS ===" << endl;
    int x1 = 10, y1 = 20;
    int z1 = x1 + y1; // Math addition -> 30
    cout << "Numbers (10 + 20)      : " << z1 << endl;

    string x2 = "10", y2 = "20";
    string z2 = x2 + y2; // Text joining -> "1020"
    cout << "Strings (\"10\" + \"20\"): " << z2 << endl;


    // ==========================================
    // 3. STRING LENGTH (length vs size)
    // ==========================================
    cout << "\n=== 3. STRING LENGTH ===" << endl;
    string txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    
    // Both length() and size() return the exact same character count
    cout << "Using length(): " << txt.length() << endl; // 26
    cout << "Using size()  : " << txt.size() << endl;   // 26


    // ==========================================
    // 4. ACCESS & MODIFY CHARACTERS
    // ==========================================
    cout << "\n=== 4. ACCESS & MODIFY CHARACTERS ===" << endl;
    string myString = "Hello";

    // Index starts at 0 -> H(0), e(1), l(2), l(3), o(4)
    cout << "First character [0] : " << myString[0] << endl; // 'H'

    // Change a single character (Use single quotes ' ' for char)
    myString[0] = 'J'; 
    cout << "After change [0]='J': " << myString << endl; // "Jello"


    // ==========================================
    // 5. SPECIAL CHARACTERS (Escape Characters)
    // ==========================================
    cout << "\n=== 5. SPECIAL CHARACTERS ===" << endl;
    // Use backslash (\) to print quotes or backslashes safely
    string quote = "We are the so-called \"Vikings\" from the north.";
    string singleQuote = "It\'s alright.";
    string backslash = "The character \\ is called backslash.";

    cout << quote << endl;
    cout << singleQuote << endl;
    cout << backslash << endl;


    // ==========================================
    // 6. USER INPUT (cin vs getline)
    // ==========================================
    cout << "\n=== 6. USER INPUT ===" << endl;
    
    string fullName;
    cout << "Enter your full name: ";
    
    /* 
       KEY DIFFERENCE:
       - cin >> name;         -> Reads a SINGLE word (stops at space).
       - getline(cin, name);  -> Reads a FULL LINE (includes spaces).
       
       PRO TIP: If 'getline()' is skipped after using 'cin >>', 
       just put 'cin.ignore();' right before 'getline()'.
    */
    getline(cin, fullName); 
    cout << "Hello, " << fullName << "!" << endl;


    // ==========================================
    // 7. C-STYLE STRINGS (Legacy C Method)
    // ==========================================
    cout << "\n=== 7. C-STYLE STRINGS ===" << endl;
    string regularString = "Hello";  // Modern C++ string (easy to modify)
    char cStyleString[] = "Hello";   // Fixed-size character array from C language

    cout << "Regular C++ String : " << regularString << endl;
    cout << "C-Style String      : " << cStyleString << endl;

    return 0;
}