Lambdas aur Algorithms

<algorithm>, std::sort jaisi ready-made operations deta hai jo kisi bhi container ke begin()/end() iterator pair par kaam karti hain, aapko khud hand se ek sorting loop likhne ke bajaye.

main.cpp

Khud try karo →

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

int main() {
    vector<int> numbers = {5, 2, 8, 1, 9};
    sort(numbers.begin(), numbers.end());

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

Output

1 2 5 8 9

Lambda expressions

Ek lambda, jo [capture](params) { body } se likha jaata hai, ek anonymous inline function hai — [capture] list batati hai ki woh surrounding mein kaun se variables dekh sakta hai. std::find_if jaise ek algorithm ke saath combine karke, ek lambda aapko sirf us ek use ke liye ek separate named function likhe bina ek custom condition express karne deta hai.

main.cpp

Khud try karo →

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

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

    auto it = find_if(numbers.begin(), numbers.end(), [threshold](int n) {
        return n > threshold;
    });

    if (it != numbers.end()) {
        cout << "First number greater than " << threshold << " is " << *it << endl;
    }
    return 0;
}

Output

First number greater than 3 is 4

Aage: smart pointers — manual new aur delete ka modern, RAII-based alternative.

Practice exercise

Ek vector<int> numbers = {1, 2, 3, 4} diya gaya hai, ek naya vector banao jisme har number ka square ho, phir sabko spaces se separate karke print karo.

← STL Containers aur Iterators Smart Pointers →