Arrays aur Vectors

Ek C-style array ka size compile time par fixed hota hai aur grow karne ka koi built-in tarika nahi hota. sizeof(array) / sizeof(array[0]) iski length calculate karne ka classic (thoda clunky hi sahi) idiom hai, kyunki ek array runtime par apna size track nahi karta.

#include <iostream>
using namespace std;

int main() {
    int numbers[5] = {1, 2, 3, 4, 5};
    cout << "numbers[2] = " << numbers[2] << endl;
    cout << "size = " << sizeof(numbers) / sizeof(numbers[0]) << endl;
    return 0;
}

numbers[2] = 3
size = 5

std::vector

std::vector C++ ka primary growable collection hai — yeh apna khud ka heap-allocated storage manage karta hai aur jab aap elements push_back karte ho to khud ko automatically resize kar leta hai. Yeh ek template hai, isliye vector<int> aur vector<string> dono valid, type-safe instantiations hain.

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

int main() {
    vector<int> numbers = {1, 2, 3};
    numbers.push_back(4);
    numbers.push_back(5);

    for (int n : numbers) {
        cout << n << " ";
    }
    cout << endl;
    cout << "size = " << numbers.size() << endl;
    return 0;
}

1 2 3 4 5 
size = 5

Aage: strings — std::string, ek real owned, mutable string type.