C++: Lambda Expressions vs Function Pointers

What are the main differences between lambda expressions and function pointers in C++?

Lambda expressions are anonymous functions that can capture variables from their surrounding scope, while function pointers are variables that store the address of a function. Lambdas provide more flexibility and can be used inline, whereas function pointers require a separate function definition.

Can you give me an example of how to use a lambda expression?

Sure! Here's a simple example:

#include <iostream>
#include <vector>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    auto sum = [](int a, int b) { return a + b; };
    int total = 0;
    for (int num : numbers) {
        total = sum(total, num);
    }
    std::cout << "Total: " << total << std::endl;
    return 0;
}

This code uses a lambda to sum the elements of a vector.

What about function pointers? How do they work?

Function pointers are declared by specifying the return type and parameter types. For example:

#include <iostream>

void greet() {
    std::cout << "Hello!" << std::endl;
}

int main() {
    void (*funcPtr)() = &greet;
    funcPtr(); // Calls the greet function
    return 0;
}

Here, funcPtr is a pointer to the greet function.

When should I use lambda expressions instead of function pointers?

Use lambda expressions when you need a quick, inline function that captures variables or when working with STL algorithms. Function pointers are better for passing functions around when you need to reference existing functions without capturing context.