c++ - std::find Object by Member -

scenario

i’ve run speedbump while using stl seems normal scenario, simplified here:

class person {   string name;   int    age; };  vector<person> people; addpeople(people);  string s("bob"); find(people.begin(), people.end(), s); 

problem

unfortunately find wants compare entire class.

question

there better or more appropriate way “stl way”? suggested questions weren’t helpful, managed find couple of related questions no direct solution.

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work-arounds/tests

there’s potential work-arounds:

1. forgo find altogether (cluttered, refactored):

   bool bbob = false; (uint = 0; < people.size(); i++) {   if (people[i].name == s)   bbob = true;   break; } 

2. provide conversion operator (implicit conversion doesn’t work; explicit can’t used in find):

   class person {   string name;   int    age;   operator string() {return name;} };  person b ("bob", 99); string s ("bob");        b  == s;     //doesn’t work string(b) == s;     //works, no find() 

3. define standalone equality operator (simple, effective, globally exposed):

   bool operator==(person l, string r) {   return l.name == r; } 

4. define member equality operator (makes comparison order dependent; object must first):

   class person {   string name;   int    age;   bool operator==(string s) {return name == s;} };  person b ("bob", 99); string s ("bob"); b==s;               //works s==b;               //doesn’t work, not problem find() 

it looks #4 best candidate, none seem ideal or feel “stl”, , have problems.

is there better or more appropriate way “stl way”?

you can use std::find_if (powered c++11 lambdas):

std::string name = "bob"; // ... std::find_if(std::begin(people), std::end(people),      [&] (person const& p) { return p.name == name; } 

notice, calling "stl way" inappropriate. c++ standard library, not stl ("standard template library"). stl served strong inspiration containers , algorithms library of c++ standard library, 2 things not same. see this q&a on stackoverflow further information.

edit:

since using compiler not support lambdas, can define own functor predicate:

struct person_has_name {     person_has_name(std::string const& n) : name(n) { }       bool operator () (person const& p) { return p.name == name; } private:     std::string name; }; 

and use std::find_if way:

std::string name = "bob"; // ... std::find_if(people.begin(), people.end(), person_has_name(name));