新手询问一下两种输出和有何不同？解决思路

新手询问一下两种输出和有何不同？
一种是#include <iostream>
int main()
{
// prompt user to enter two numbers
std::cout << "Enter two numbers:" << std::endl;

int v1, v2;
std::cin >> v1 >> v2;

std::cout << "The sum of " << v1 << " and " << v2
<< " is " << v1 + v2 << std::endl;

return 0;
}
另一种是#include<iostream>
int main()
{
std::cout<<"测试输出";
std::cout<<2*2*2*2*2*2*2*2;
std::cout<<std::endl;
return 0;
}

------解决方案--------------------
cout << A << B << C << D;
和结果是一样的，细节上会有些区别，一般不用管他
cout << A;
cout << B;
cout << C;
cout << D;

cout << A << B 
<< C << D;
也可以这样写