#include <iostream>
 
struct A { friend std::ostream& operator << (std::ostream& o, const A& c) { return o; }; };
struct B { friend std::ostream& operator << (std::ostream& o, const B& c) { return o; }; };
 
int main(int argc, char** argv)
{
 
    A *arrayA = new A[10];
    B *arrayB = new B[10];
 
    /* some codes to initialize arrayA and arrayB */
    for (int i = 0; i < 10; i++) { std::cout << arrayA[i]; } // this work
    for (int j = 0; j < 10; j++) { std::cout << arrayB[j]; } // this complain
    return 0;
}
 

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