Imagine class with string value.
class Test {
public:
string name;
};
Is is stored in vector
vector<Test> d;
I would like to use sort() function to sort objects in vector alphabeticaly by its name value. I know that sort() function has third parameter some kind of sorting function but i dont know how to write this function.
sort(d.begin(),d.end(),comp());
comp () { ? }
You can create a comparator
bool comp(const Test &test1, const Test &test2){
return test1.getName() < test2.getName();
}
Or you can overload the operator < in your class
bool operator < (const Test &test){
return name < test.name;
}
Note that if you overload the operator <, then you don't need to add the third parameter in the sort function.
comp will be a function that will return a bool to indicate the comparison in two parameters. In your case, it should look like:
bool compare ( const Test& s1, const Test& s2 )
{
return ( s1.name < s2.name );
}
and your call will be: sort ( d.begin(), d.end(), compare );
const Test& s1 instead of simply Test s1 for the parameters to avoid copying the object.