Variables & Types

#include <iostream>
#include <string>
using namespace std;

int main() {
    // Fundamental types (same as C)
    int i = 42;
    double d = 3.14159;
    float f = 3.14f;
    bool b = true;
    char c = 'A';
    long long ll = 1234567890LL;

    // C++ adds: string (not a char array)
    string name = "Alice";          // no buffer size needed
    string greeting = "Hello, " + name + "!";  // concatenation with +
    cout << greeting << "
";
    cout << "Length: " << name.length() << "
";  // 5

    // auto — type inference (C++11)
    auto x = 42;        // int
    auto y = 3.14;      // double
    auto z = "hello";   // const char*
    auto s = string("hello");  // std::string

    // const
    const int MAX = 100;
    const double PI = 3.14159265358979;

    // References — alias for another variable
    int original = 10;
    int& ref = original;  // ref IS original
    ref = 99;
    cout << original << "
";  // 99 — original changed through ref

    cout << i << " " << d << " " << b << "
";
    return 0;
}

#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main() {
    // std::vector — dynamic array (the C++ way to use arrays)
    vector<int> nums = {1, 2, 3, 4, 5};
    nums.push_back(6);
    nums.pop_back();

    cout << nums[0] << "
";        // 1
    cout << nums.size() << "
";    // 5
    cout << nums.front() << "
";   // 1
    cout << nums.back() << "
";    // 5

    // Range-based for loop (C++11)
    for (int n : nums) {
        cout << n << " ";
    }
    cout << "
";

    // Vector of strings
    vector<string> fruits = {"apple", "banana", "cherry"};
    fruits.push_back("date");
    for (const string& f : fruits) {   // const& to avoid copying
        cout << f << "
";
    }

    return 0;
}