┌── Capture Clause (Context access)
│ ┌── Parameter List
│ │ ┌── Trailing Return Type (Optional)
│ │ │ ┌── Function Body
┌─┴─┐ ┌─┴──┐ ┌──┴──┐ ┌───┴────────────────┐
[ x ] (int y) -> int { return x + y; }[]: Captures nothing.[=]: Captures all used outer variables by value (read-only copy).[&]: Captures all used outer variables by reference (can mutate original).[this]: Captures the current class object pointer.[val = 10]: Generalized lambda capture (C++14).#include <iostream>
#include <vector>
#include <algorithm>
int main() {
std::vector<int> numbers = {12, 45, 68, 23, 89, 90, 34};
int threshold = 50;
int matchCount = 0;
// Lambda capturing 'threshold' by value and 'matchCount' by reference
auto countHigh = [&matchCount, threshold](int n) {
if (n > threshold) {
++matchCount;
return true;
}
return false;
};
std::cout << "Numbers above " << threshold << ":\n";
for (int num : numbers) {
if (countHigh(num)) {
std::cout << " - " << num << "\n";
}
}
std::cout << "Total matches: " << matchCount << "\n";
// Generic Lambda (C++14 auto parameter)
auto printTwice = [](auto item) {
std::cout << item << " | " << item << "\n";
};
printTwice("OperateTools");
printTwice(42);
return 0;
}[x, &y]) over default captures ([=], [&]) to avoid accidental lifetime dangling bugs.[](auto val)) for concise polymorphic callables.std::bind in modern C++ for better compiler optimization and readability.