Is there a “accummulate_if”?

Question

Is there a function similar to accummulate() but provides a unary pre-condition to filter the linear container when performing the operation? I search for

Answer 1

Do you really must to use an algorithm? Something as simple as bellow won't do?

for (const auto& v: V)  if(pred(v)) sum+=v;

Sam's idea is also good. But I would do it with lambda:

 sum = accumulate(
     V.begin(), V.end(), 0, 
     [](int a, int b){return pred(b)? a+b: a;}
 );