Quick Answer

Create anonymous functions in C++.

Understanding the Issue

Lambdas allow defining function objects inline, especially useful with STL algorithms. They can capture variables from their enclosing scope.

The Problem

This code demonstrates the issue:

Cpp Error 
// Need a short function for sorting

The Solution

Here's the corrected code:

Cpp Fixed 
#include <vector>
#include <algorithm>
#include <iostream>

int main() {
    std::vector<int> numbers = {4, 2, 5, 1, 3};
    
    // Lambda for custom sorting
    std::sort(numbers.begin(), numbers.end(), 
        [](int a, int b) {
            return a > b; // Descending order
        });
    
    // Lambda with capture
    int threshold = 3;
    auto count = std::count_if(numbers.begin(), numbers.end(),
        [threshold](int n) {
            return n > threshold;
        });
    
    std::cout << count << " numbers > " << threshold << std::endl;
    return 0;
}

Key Takeaways

Lambdas provide concise syntax for inline function objects.