Question

I am a Java and C# programmer. Recently, I am working on C++ project. I am having a problem of how to write the sample code following in C++. The sample code following is to sort a property of a struct:

public struct Person
{
    public string name;
    public int age;
}

Add some Persons to a list and sort by the age:

static void main()
{
   List<Person> persons = new List<Person>();

   Person person = new Person();
   person.age = 10;
   person.name = "Jane";

   persons.Add(person);

   person = new Person();
   person.age = 13;
   person.name = "Jack";

   persons.Add(person);

   person = new Person();
   person.age = 12;
   person.name = "Anna";

   persons.Add(person);

   // sort age
   persons.Sort(delegate(Person p1, Person p2) 
   { return p1.age.CompareTo(p2.age); });

   persons.ForEach(delegate(Person p) 
   { Console.WriteLine(String.Format("{0} {1}", p.age, p.name)); });
}

How can I write an equivalent sample code in C++?

Answer 1

Given the Person type :

struct Person
{
    Person(int age_, const std::string &name_)
        : age(age_), name(name_)
    {}

    int age;
    std::string name;
};

int main()
{
    std::list<Person> persons;
    persons.push_back(Person(10, "Jane"));
    persons.push_back(Person(13, "Jack"));
    persons.push_back(Person(12, "Anna"));
}

Solution 1

bool compareAge(const Person &lhs, const Person &rhs)
{
    return lhs.age < rhs.age;
}

int main()
{
    /* persons list initialization */
    persons.sort(&compareAge);
}

Solution 2 (using boost::bind)

int main()
{
    /* persons list initialization */
    persons.sort(boost::bind(&Person::age, _1) < boost::bind(&Person::age, _2));
}

There also is a solution using C++0x lambdas.