What does this do

[RexLee]

I was looking at some code. (C++)

struct isValue{    isValue(int x): _x(x){};    bool operator()(std::pair<int,int> v)    {        return v.second == _x;    }             int _x;};

But I don't understand this line:

isValue(int x): _x(x){};

What does it do?

[WanderingFool]

It is a constructor.  Basically it is turning the struct into a pseudo-class

 

The _x(x) is just initiallizing the _x to x...it is suppose to be more efficient than doing

 

_x = x inside the actual constructor (or at least that is what my teacher said a long time ago...not sure if it is actually true)

[RexLee]

Thanks.