How do you write a simple lambda that adds two numbers?

auto add = [](int a, int b) { return a + b; }; — then call it like any function: add(3, 4).

auto add = [](int a, int b) { return a + b; };
int result = add(3, 4);   // result = 7

Breakdown:

• auto add — let the compiler deduce the lambda's (unnameable) type
• [] — no captures needed; it uses only its parameters
• (int a, int b) — two int parameters
• { return a + b; } — body returns the sum

Using it immediately, without naming it:

int result = [](int a, int b) { return a + b; }(3, 4);