Cpp2_4.html

<article>
    <h1>C++ II: Page 4 - STL: Algorithms</h1>

    <section>
        <h2>Generic Algorithms</h2>
        <p>The STL algorithms library provides a collection of efficient, generic functions to perform common operations on sequences of elements, such as searching, sorting, and transforming.</p>
        
        <h3>The Code implementation</h3>
        <pre><code class="language-cpp">/*
 * File: algorithms.cpp
 * Demonstration of STL algorithms: sorting, searching, transforming, and numeric ops
 */
#include &lt;iostream&gt;
#include &lt;vector&gt;
#include &lt;algorithm&gt;
#include &lt;numeric&gt; // For accumulate

using namespace std;

int main() {
    vector&lt;int&gt; nums = {5, 2, 8, 1, 9, 2};

    // 1. Sort (using default operator<)
    sort(nums.begin(), nums.end());
    cout << "Sorted: ";
    for (int n : nums) cout << n << " ";
    cout << endl;

    // 2. Find
    auto it = find(nums.begin(), nums.end(), 8);
    if (it != nums.end()) {
        cout << "Found 8 at index: " << distance(nums.begin(), it) << endl;
    }

    // 3. Transform (doubling elements)
    transform(nums.begin(), nums.end(), nums.begin(), [](int n) { return n * 2; });
    
    // 4. Numeric operations (accumulate)
    int sum = accumulate(nums.begin(), nums.end(), 0);
    cout << "Sum after doubling: " << sum << endl;

    // 5. Predicate algorithms
    bool allEven = all_of(nums.begin(), nums.end(), [](int n) { return n % 2 == 0; });
    bool anyNegative = any_of(nums.begin(), nums.end(), [](int n) { return n < 0; });
    
    cout << "All even: " << (allEven ? "Yes" : "No") << endl;
    cout << "Any negative: " << (anyNegative ? "Yes" : "No") << endl;

    return 0;
}

/*
 * Algorithm Nuances:
 * 1. Algorithms operate on iterators (e.g., begin(), end()).
 * 2. They are generally more efficient and safer than manual loops.
 * 3. Most algorithms expect a range [first, last), where 'last' is excluded.
 * 4. Custom predicates (like lambdas) can be passed to customize behavior.
 * 5. STL algorithms are highly optimized, often leveraging compiler intrinsics.
 * 6. 'accumulate' and other numeric algorithms live in &lt;numeric&gt;.
 */
        </code></pre>
        <div class="interactive-sim">
            <h3>Algorithm Simulator</h3>
            <button class="sim-button" onclick="
                const out = document.getElementById('sim-output-cpp2_4');
                out.innerHTML = 'nums = {5, 2, 8};<br>';
                setTimeout(() => out.innerHTML += '>> sort(nums.begin(), nums.end());<br>>> Sorted: {2, 5, 8}', 800);
            ">Run Simulation</button>
            <div id="sim-output-cpp2_4" class="sim-output"></div>
        </div>
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