单选题

Which is the correct&nbspoutput of t...

Question

Which is the correct output of the following program.

#include <iostream>
#include <string>
using namespace std

class ObjectCount{
private:
    static int objCount
public:
    ObjectCount() { objCount++ }
    static void print(const string& msg = "") {
        if(msg.size() != 0) cout << msg << ": "
        cout << "objCount = " << objCount << endl
    }    
    ~ObjectCount() { objCount-- }
}

int ObjectCount::objCount = 0

ObjectCount f(ObjectCount oc) {
    return oc
}

int main(){
    ObjectCount o1
    ObjectCount::print("after construction of o1")
    ObjectCount o2 = f(o1)
    ObjectCount::print("after call f()")
}

A. after construction of o1: objCount = 1 after call f(): objCount = 0

B. after construction of o1: objCount = 1 after call f(): objCount = 1

C. after construction of o1: objCount = 1 after call f(): objCount = 2

D. after construction of o1: objCount = 1 after call f(): objCount = 3