Ignoring the Voices: C++11 Example - Lambda Parameters

lambda_functions.cpp

#include <functional>
#include <iostream>
#include <vector>

#include <math.h>

using namespace std;

double Sum(const vector<double>& values, function<double (double x)> f)
{
    double result = 0.0;
    for (auto d : values)
    {
        result += f(d);
    }
    return result;
}

double Complex(double x)
{
    double result = sin(x * 3.14159265);
    result -= floor(result);
    
    return result;
}

int main(int argc, char** argv)
{
    vector<double> myValues = { 1.3, 2.1, 7.4, 9.6 };
    
    double result1 = Sum(myValues, [](double x) { return x; });
    double result2 = Sum(myValues, Complex);
    
    cout << "Result 1 (lambda):   " << result1 << endl;
    cout << "Result 2 (function): " << result2 << endl;
}

Compiled as follows with GCC 4.6.1 on Ubuntu 11.10

g++ -Wall -Werror -std=c++0x -o lambda_functions lambda_functions.cpp